Carlos Alcaraz believes New York provides a perfect stage for the first grand slam semi-final of his career after the Spanish teenager edged a late-night thriller with Jannik Sinner.

In the last of the men's singles quarter-finals at Flushing Meadows, Alcaraz prevailed in the latest finish on record at the tournament, sealing a 6-3 6-7 (7-9) 6-7 (0-7) 7-5 6-3 victory at 02:50 local time on Thursday.

Sinner was left crestfallen, saying the defeat was in his "top list" and would hurt "for quite a while". He had served for the match in the fourth set but could not see it out, the 21-year-old seeing Alcaraz exact revenge for defeat in the fourth round at Wimbledon.

At the age of 19, Alcaraz is leading the men's tour for wins this season, one short of reaching 50 for the year, and the Arthur Ashe Stadium crowds have taken him to their hearts.

He is the youngest men's grand slam singles semi-finalist since Rafael Nadal marched to the 2005 French Open title, and the youngest man to reach the last four at the US Open since Pete Sampras in 1990, also on a run to the trophy.

The clash with Sinner was an epic that spanned five hours and 15 minutes, yet Alcaraz said afterwards: "During the whole match, I feel great physically.

"I feel great to be in my first semi-final in a grand slam. I feel better reaching the semi-final here in the US Open. This tournament is amazing. The crowd is amazing, I would say the best in the world.

"The energy I receive in this court at 3am, it was unbelievable. Probably in other tournaments, other places, everybody would have gone to their house to rest. But they keep in the court, supporting me. It was unbelievable.

"I feel great to have a semi-final here in the US Open."

Frances Tiafoe awaits him, after the American took down Andrey Rublev in straight sets on Wednesday, following up his fourth-round win over Rafael Nadal with another accomplished display. The crowd will likely have split allegiances for that semi-final on Friday.

"It's going to be really, really tough," said Alcaraz. "Everybody knows the level of Frances. He has beaten Rafa Nadal, Rublev in three sets. He's playing unbelievable right now, high in confidence.

"He loves the crowd. He loves this court. I'm going to have to play my best. But right now I'm thinking about this match. I'm enjoying this moment. I have a day of rest to think about the semi-final."

Alcaraz also said the possibility of becoming world number one did not cross his mind during the Sinner battle. He would hit the top spot by winning the title, and would also be assured of number one by reaching the final if Casper Ruud loses to Karen Khachanov in the other semi-final.

Sinner can only dream of reaching such heights for now, although his time may come.

He has a 9-20 losing record against top-10 opponents after this setback, but wins over Alcaraz at Wimbledon and later at a smaller event in Umag, Croatia, suggest his game is developing nicely.

The Italian had a strong tournament in New York but was left with regrets after failing to see this one through.

"I've had some tough losses, for sure. This is in the top list," Sinner said. "I think this one will hurt for quite a while.

"But tomorrow I wake up, or today I wake up, trying to somehow take only the positives, trying to take away the other part.

"But it's tough, for sure. In my next tournament I will play Davis Cup. Before, I want to practise again in the best possible way, trying to improve. Maybe next time I can win this, no?"

Carlos Alcaraz survived a Jannik Sinner match point before going on to clinch his maiden grand slam semi-final berth with an epic five-set victory in more than five hours at the US Open.

The Spanish third seed triumphed 6-3 6-7 (7-9) 6-7 (0-7) 7-5 6-3 in the latest-ever finish at the US Open, officially ending at 2:50am Thursday local time.

The match was within nine minutes of being the longest ever in US Open history, the record held by Michael Chang and Stefan Edberg from 1992 of five hours and 26 minutes.

The 19-year-old fought back from a Sinner match point in the fourth set, rallying to force a fifth, where he broke the Italian 11th seed in the eighth game before serving it out for victory.

Alcaraz blew opportunities too, including five set points in the second set, while he failed to serve out the third set before Sinner won the tie-break 7-0 to take all the momentum into the fourth.

But the emerging Alcaraz showcased his doggedness even after falling a break behind in the fourth, to set up a semi-final date against 22nd seed Frances Tiafoe, who has beaten Andrey Rublev and Rafael Nadal in his past two matches.

The win also means Alcaraz is a step closer to claiming the world number one ranking for the first time, which will be achieved if he wins the title, or even if he makes the final and fifth seed Casper Ruud does not.

Data slam: Alcaraz cannot help Nadal comparisons

Alcaraz, 19, is not fond of comparisons to compatriot Rafael Nadal, but his victory means he becomes the youngest grand slam semi-finalist since the 22-time major winner in 2005. 

Little separated Alcaraz and Sinner who will both have won huge admiration, but the Italian's 63 unforced errors compared to the Spaniard's 38 was an outlier.

ACES/DOUBLE FAULTS

Alcaraz – 5/5
Sinner – 8/11

WINNERS/UNFORCED ERRORS

Alcaraz – 58/38
Sinner – 61/63

BREAK POINTS WON

Alcaraz – 11/26
Sinner – 7/16

Frances Tiafoe celebrated a "crazy" win after his defeat of Andrey Rublev saw him become the first American man to reach the US Open semi-finals in 16 years.

Tiafoe stunned Rafael Nadal on Monday and followed up that career-high by reaching the last four of a major for the first time on Wednesday.

Ninth seed Rublev, who has lost all six of his grand slam quarter-finals, stood in his way but Tiafoe prevailed 7-6 (7-3) 7-6 (7-0) 6-4 at Arthur Ashe Stadium.

The 24-year-old is the first male player from the United States to reach a semi-final at Flushing Meadows since Andy Roddick in 2006.

Roddick went on to reach the final that year, though fell short of winning a second US Open final as he lost to Roger Federer.

This time around, Tiafoe will face either Jannik Sinner or Carlos Alcaraz, who has a shot at becoming the new world number one. 

"This is wild, this is crazy," world number 26 Tiafoe said after his win. 

"I had the biggest win of my life 48 hours ago and coming out and getting another big win. Andrey's a hell of a player, and to back it up, that's huge. It's tough to turn the page, but I did and now I'm in the semis.

"I feel so at home on courts like this. This court is unbelievable. [The crowd] gets so far behind me, I want to play, I want to give my best. I always find a way somehow on this court, I always play some great tennis and I have been. Let's enjoy this, we've got two more."

Tiafoe might well be the only home hope left for the American crowd to back in New York come the end of play on Wednesday, with Jessica Pegula facing the daunting task of taking on world number one Iga Swiatek in the women's singles.

Nick Kyrgios claims all tournaments other than grand slams are a "waste of time" following his US Open quarter-final exit to Karen Khachanov on Tuesday.

The in-form 2022 Wimbledon runner-up's run at Flushing Meadows, which included knocking out defending champion Daniil Medvedev, was ended by Khachanov 7-5 4-6 7-5 6-7 (3-7) 6-4.

Kyrgios had been in career-best form, winning more matches than any other player on the ATP Tour since his Wimbledon final defeat to Novak Djokovic, but will need to wait until January for another crack at a major, at his home Australian Open.

The 27-year-old has spoken about his renewed level of focus since reaching the Wimbledon final and said he was "devastated" by his US Open loss, smashing a racquet after the match.

"I honestly feel like s***," he said. "I feel like I've let so many people down.

"I feel like these four tournaments are the only ones that are ever going to matter. It's just like you got to start it all again. I have to wait until the Australian Open. It's just devastating. It's heart-breaking.

"I don't even really care about any other tournament. I feel like at the grand slams, now having success at a grand slam, it's just like no other tournament really matters.

"It's like you get better, you get worse, then at a grand slam none of it matters. You either win or lose. People don't really care if you got better on the day or you lost 6-4 in the fifth or played one of the best matches of the tournament. You lost.

"That's all people remember at a grand slam, whether you win or you lose. I think pretty much every other tournament during the year is a waste of time really. You should just run up and show up at a grand slam. That's what you're remembered by."

Kyrgios allayed concerns over a knee injury at the end of the first set that he said settled, stating that he started "flat" and felt Khachanov's serve was too good, particularly in key moments.

"All credit to Karen, he's a fighter. He's a warrior," he said.

"I thought he served really good today. Honestly probably the best server I played this tournament, to be honest, the way he was hitting his spots under pressure."

The triumph marks 29th seed Khachanov's first major semi-final having fallen in the quarter-finals at majors twice previously.

"It's like one more step forward," the Russian said. "I'm really, really happy I could do it.

"I had to face and to beat Nick, who is playing some of the best tennis again. It obviously was a tough match to approach. I made my first semi-final, so it's pretty simple in my head. I'm just really happy."

Karen Khachanov reached a grand slam semi-final for the first time as he ended Nick Kyrgios' US Open run in a five-set three-and-a-half-hour epic on Tuesday evening.

The 27th-seeded Russian, who had fallen in the quarters at the 2019 French Open and 2021 Wimbledon Championships, prevailed 7-5 4-6 7-5 6-7 (3-7) 6-4 over the Australian 23rd seed to set up a semi-final date with fifth seed Casper Ruud.

The result ended the run of Kyrgios who had won the most matches on the ATP Tour since losing July's Wimbledon final to Novak Djokovic. Kyrgios had taken out reigning champion and top seed Daniil Medvedev in the fourth round.

The 26-year-old Russian broke Kyrgios' serve in the 12th game of the first set with an exquisite lob clinching the frame where the Australian's second serve let him down.

Kyrgios responded to win the second set, despite a medical timeout for treatment on his left leg after exclaiming "I can't walk", breaking the Russian early and hitting 12-5 winners.

Khachanov claimed the third set in similar circumstances to the first, with Kyrgios failing to hold his serve in the 12th game, this time producing unforced errors in the key moments.

The two players traded breaks early in the fourth set but Kyrgios would force a fifth set after a dominant tie-break where he converted his second set point.

The Russian got an early break in the fifth set, while Kyrgios failed to convert break points in Khachanov's next two service games and he would not recover.

Data Slam: Khachanov cool under pressure

Little split these two players in an extremely tight quarter-final, with 31-30 aces edged by Kyrgios, but many of Khachanov's came at crucial moments under pressure.

Kyrgios' flamboyance and shot-making ability was on show, but his inability to convert break points, along with 58 unforced errors, ultimately proved the difference, taking two of nine.

ACES/DOUBLE FAULTS

Kyrgios – 31/5
Khachanov – 30/3

WINNERS/UNFORCED ERRORS

Kyrgios – 75/58
Khachanov – 62/31

BREAK POINTS WON

Kyrgios – 2/9
Khachanov – 4/8

Karen Khachanov reached a grand slam semi-final for the first time as he ended Nick Kyrgios' US Open run in a five-set three-and-a-half-hour epic on Tuesday evening.

The 27th-seeded Russian, who had fallen in the quarters at the 2019 French Open and 2021 Wimbledon Championships, prevailed 7-5 4-6 7-5 6-7 (3-7) 6-4 over the Australian 23rd seed.

The result ended the run of Kyrgios who had won the most matches on the ATP Tour since losing July's Wimbledon final to Novak Djokovic. Kyrgios had taken out reigning champion and top seed Daniil Medvedev in the fourth round.

The 26-year-old Russian broke Kyrgios' serve in the 12th game of the first set with an exquisite lob clinching the frame where the Australian's second serve let him down.

Kyrgios responded to win the second set, despite a medical timeout for treatment on his left leg after exclaiming "I can't walk", breaking the Russian early and hitting 12-5 winners.

Khachanov claimed the third set in similar circumstances to the first, with Kyrgios failing to hold his serve in the 12th game, this time producing unforced errors in the key moments.

The two players traded breaks early in the fourth set but Kyrgios would force a fifth set after a dominant tie-break where he converted his second set point.

The Russian got an early break in the fifth set, while Kyrgios failed to convert break points in Khachanov's next two service games and he would not recover.

Data Slam: Khachanov cool under pressure

Little split these two players in an extremely tight quarter-final, with 31-30 aces edged by Kyrgios, but many of Khachanov's came at crucial moments under pressure.

Kyrgios' flamboyance and shot-making ability was on show, but his inability to convert break points, along with 58 unforced errors, ultimately proved the difference, taking two of nine.

ACES/DOUBLE FAULTS

Kyrgios – 31/5
Khachanov – 30/3

WINNERS/UNFORCED ERRORS

Kyrgios – 75/58
Khachanov – 62/31

BREAK POINTS WON

Kyrgios – 2/9
Khachanov – 4/8

Casper Ruud booked his place in the semi-finals of the US Open with a 6-1 6-4 7-6 (7-4) defeat of Matteo Berrettini on Tuesday.

Ruud was at the top of his game in the opening two sets, taking the first inside half an hour, but Berrettini made a contest of the third.

Indeed, the Italian at one stage had two set points, having taken a 5-2 advantage.

Yet Ruud, who did not require a single ace in this match, clawed both back to hold his serve and immediately broke to swing the momentum in his favour once more.

Berrettini had failed to execute two routine drop-shots as he conceded serve and never regained his composure, with Ruud forcing the tie-break.

It was then that the world number seven got back on top form, racing into a 3-0 lead and, despite a wobble that saw two match points fall by the wayside, holding his nerve to seal the win at the third attempt.

Into his first US Open semi-final – and his second at a grand slam following a run to the final at Roland Garros this year – Ruud, who along with Carlos Alcaraz has a chance of becoming the new world number one, will face either Nick Kyrgios or Karen Khachanov in the last four.

Data Slam: Berrettini's top-10 hoodoo

Berrettini was aiming to reach his fourth grand slam semi-final and a second at Flushing Meadows, yet his record against top-10 opponents is a poor one, and it did not change for the better in New York.

He is now 7-19 for his career against opponents ranked inside the top 10 by the ATP, while he has lost his last 11 such matches since defeating Dominic Thiem – then ranked number three – at the 2021 ATP Cup. Berrettini has never defeated a top-10 opponent in a grand slam (0-8).

ACES/DOUBLE FAULTS

Ruud – 0/2
Berrettini – 13/3

WINNERS/UNFORCED ERRORS

Ruud – 20/23
Berrettini – 35/39

BREAK POINTS WON

Ruud – 5/14
Berrettini – 2/9

The career of Carlos Alcaraz could be one that takes up a great deal of space in the record books, and he is getting started early.

Not yet old enough to buy a stiff drink in a New York bar, the 19-year-old was the toast of Flushing Meadows after a late-night win over Marin Cilic that ran into the early hours of Tuesday.

That five-set win against the 2014 champion, combined with the shock exit of Rafael Nadal at Frances Tiafoe's hands, has raised expectations that Alcaraz could scoop a first grand slam title on Sunday.

Should he land that breakthrough major, there will be another feather in his cap, making Alcaraz the youngest world number one since the ATP rankings were established in 1973, and the first teenager to hold down top spot. He has climbed from 32nd at the start of the year to his current position of fourth on the list.

Nadal is poised to go to number one, which he last held in February 2020, unless Alcaraz or 23-year-old Norwegian Casper Ruud reach the title match. They are the only two players remaining in the draw who can clamber to the top ranking, which Daniil Medvedev will relinquish after his fourth-round exit to Nick Kyrgios.

If both reach the final, the champion will go to number one.

In the city that never sleeps, Alcaraz completed a 6-4 3-6 6-4 4-6 6-3 win over Croatian Cilic at 02:23 local time, three minutes short of matching the latest finish in US Open history, shared jointly by three matches: Mats Wilander vs Mikael Pernfors (1993), John Isner v Philipp Kohlschreiber (2012), Kei Nishikori v Milos Raonic (2014).

The victory on Arthur Ashe Stadium made Alcaraz the youngest man to reach back-to-back US Open quarter-finals since Australians Lew Hoad and Ken Rosewall both achieved the feat before turning 19 in 1953. It was called the US Championships in that era.

Alcaraz has won a tour-leading 48 matches in 2022 and has become the youngest man to reach three grand slam quarter-finals since Michael Chang over 30 years ago.

However, he next faces a player making his own history.

Alcaraz's quarter-final opponent is a recent nemesis: Jannik Sinner, the 21-year-old Italian who beat him in round four at Wimbledon and again in the final of the clay-court event in Umag, Croatia, at the end of July.

"I played a couple of times against him," Alcaraz said. "He's a great player, really tough one. I lost twice in two months [to him] so I will have to be ready for this battle against Jannik."

There is a victory that Alcaraz could point to, having defeated Sinner on an indoor hard court at the Paris Masters last November, but they have never played on an outdoor hard court, which is where they will do battle on Wednesday.

Sinner has now reached the quarter-final stage of all four majors, becoming the youngest man to pull off that feat since a 20-year-old Novak Djokovic completed the set in 2008.

The last-eight duel with Alcaraz could be a sizzling clash, albeit Alcaraz and Sinner had some recharging to do on Tuesday after both were pushed to five sets in round four, in Sinner's case by Ilya Ivashka of Belarus. Alcaraz now has a 6-1 win-loss record in five-set matches.

Nobody remaining in the men's quarter-finals has a slam title to their name, and Alcaraz will hope he continues to have the backing of the crowd in Queens.

He said after fending off Cilic: "Of course, the support today in Arthur Ashe was crazy. After losing the fourth set, it was tough for me to come back in the fifth set, to stay strong mentally. But the energy I received today made me win."

Rafael Nadal's loss to Frances Tiafoe opened up a host of possibilities including a first-time world number one and maiden grand slam winner as the top three's domination of men's singles continues to weaken.

World number three Nadal bowed out in the fourth round to 22nd seed Tiafoe 6-4 4-6 6-4 6-3 on Monday, while third seed Alcaraz triumphed over Marin Cilic 6-4 3-6 6-4 4-6 6-3 in a match that went to almost 2:30am local time.

Cilic was the last remaining male player with a grand slam title to his name, meaning this year's US Open will bring a new major champion.

There may also be a first-time world number one too, with Alcaraz guaranteed to claim the top rank if he wins the US Open title.

Fifth seed Casper Ruud will rise to world number one if he lifts the US Open crown at Flushing Meadows on September 11 too.

If both fall short of the final, Nadal will reclaim the top ranking from 2021 US Open champion Daniil Medvedev, who lost in the fourth round to Nick Kyrgios.

Alcaraz could also scale the rankings summit should he reach the final, assuming Ruud misses out.

Frances Tiafoe is dreaming big after upsetting Rafael Nadal in the US Open fourth round on Monday to open up the men's singles draw.

The 22nd-seeded American stunned the 22-time grand slam champion, winning 6-4 4-6 6-4 6-3 in three hours and 34 minutes.

The victory meant Tiafoe reached the US Open quarter-finals for the first time, having fallen in the fourth round in the past three years. It also equaled his best-ever major return, having made the 2019 Australian Open quarters as well.

It also opens up the men's singles draw for a potential new grand slam winner, with Marin Cilic – who is due to play third seed Carlos Alcaraz on Monday evening – the last remaining major champion.

"Everyone is looking at it I'm sure," Tiafoe told reporters about the draw. "Everyone looks at it. Here we go, right? So am I. I'm just taking it day by day.

"Slams, crazy things can happen. Especially here in New York, so it's going to be a fun ride come Wednesday."

Tiafoe will take on ninth seed Andrey Rublev on Wednesday in the last eight, where he will hope to re-produce the "unbelievable" form he displayed against Nadal.

"I'm beyond happy, almost in tears, I can't believe it," Tiafoe said in his on-court interview. "I played unbelievable tennis today. I really don't know what happened."

During his press conference, he added: "It was definitely one hell of a performance… I just came out there and I just believed I could do it.

"It helps I played him a couple times. Haven't played him in some years [not since 2019]. I'm a different person now, different player."

Tiafoe had never beaten Nadal before, nor had he taken a set off the Spanish world number three. The victory was Tiafoe's third against a top-five opponent.

"For a while there, I was like, geez, you see all these young guys get Rafa, Fed [Roger Federer], Novak [Djokovic], am I ever going to be able to say I beat one of them?" he said.

"Today I was like, no, I'm going to do that. Now it's something to tell the kids, the grandkids, I beat Rafa."

Tiafoe was also blown away after four-time NBA MVP LeBron James tweeted after his win, labeling him the "young king".

"I was losing it in the locker room. I was going crazy," he said. "That's my guy, so to see him post that, I was like do I retweet it as soon as he sent it? I was like, you know what, I'm going to be cool and act like I didn't see it and then retweet it three hours later."

Rafael Nadal was frustrated by his performance when speaking with the media after his upset loss against Frances Tiafoe in the fourth round, admitting "he was better than me".

Nadal only allowed two total break point opportunities from the first three sets, but he was unable to save either, leading to Tiafoe taking the first and third frames. 

The all-time leader in men's grand slams then was uncharacteristically shaky in the fourth, committing four double faults and more unforced errors (nine) than winners (seven).

While reporters questioned if it was the oppressive humidity, injuries, or even the distraction of the roof closing mid-match, Nadal made it clear his poor performance had a much simpler explanation.

"Well, the difference is easy," he said. "I played a bad match and he played a good match. At the end that's it, no?

"I was not able to hold a high level of tennis for a long time. I was not quick enough on my movements. He was able to take the ball too many times very early, so I was not able to push him back.

"Tennis is a sport of position a lot of times – if not, you need to be very, very quick and very young. I am not in that moment anymore.

"My shots need to be better. In some way my understanding of the game and the quality of my shots were not good enough. They were poor, I think I have to say today, because I was not able to create that much on him.

"Well done for him. He was better than me."

With the last grand slam of the year now in the books for Nadal, he said he will take some time away to recuperate, but was non-committal about when he may return.

"I need to go back [home], I need to fix things, life," he said. "Then I don't know when I'm going to come back. 

"I'm going to try to be ready mentally. When I feel that I will be ready to compete again, I will be there."

Frances Tiafoe produced a stunning performance to knock Rafael Nadal out of the US Open and reach the quarter-finals of his home grand slam for the first time.

Tiafoe was playing in the fourth round at Flushing Meadows for the third successive year, but his prospects of going beyond that point appeared slim against the 22-time grand slam champion.

Nadal had won his two previous encounters with Tiafoe but found the 24-year-old up to the challenge this time around, his firepower proving too much for his illustrious opponent.

So often Nadal has snatched victory from the jaws of defeat and there were moments during his epic that he seemed primed to do so again. Yet winning the second set and breaking at the start of the fourth both proved false dawns for Nadal, as Tiafoe prevailed 6-4 4-6 6-4 6-3 to blow a men's draw that has already lost 2021 champion Daniil Medvedev wide open.

It became clear early on that the pace of Tiafoe's ball-striking and the variety in his game would cause Nadal problems and he got the break his play deserved when the Spaniard sent a pair of forehands long in the seventh game.

Tiafoe rarely looked daunted by the occasion and though he let a pair of set points go begging after going 40-0 up at 5-4, he snatched the third with a volley to ensure Nadal would have to mount a comeback.

A classic Nadal turnaround appeared very much on the cards when Tiafoe's composure deserted him trailing 5-4 on serve in the second, a double fault from the American allowing Nadal to level the match.

But any thought of Nadal, curiously unable to make an impression on Tiafoe's second serve, dominating from there was soon extinguished, Tiafoe breaking for a 4-3 lead in the third with a searing backhand down the line.

Tiafoe consolidated with an intelligent serve and volley play on his second serve and, after a Nadal hold, made no mistake in winning the third set on his racquet with an ace.

Controversy soon followed as Nadal broke a furious Tiafoe with a vicious forehand in a game played as the Arthur Ashe Stadium roof was closing.

Tiafoe received a code violation for "audible obscenity" after venting his frustration at that decision by the tournament officials, but he harnessed his anger in the right way. Nadal sent down a pair of double faults in an uncharacteristically sloppy service game and Tiafoe capitalised with a cross-court backhand that proved too hot for the four-time champion to handle.

A backhand error from Nadal gave Tiafoe another break for a 4-3, and he subsequently raced to the finish line, getting 40-0 on Nadal's serve and then completing the fairytale with on his second match point as Nadal sent another backhand into the net.

Data Slam: Tiafoe hands Nadal first grand slam loss of 2022

After winning both the Australian Open and the French Open, and withdrawing from Wimbledon due to injury, this is Nadal's first loss at a grand slam this year.

Tiafoe also joins James Blake and Andy Roddick as the only Americans to ever defeat Nadal at a grand slam, and it snaps Nadal's streak of 16 consecutive grand slam quarter-final appearances.

ACES/DOUBLE FAULTS

Tiafoe – 18/4

Nadal – 9/9

WINNERS/UNFORCED ERRORS

Tiafoe – 48/28

Nadal – 33/26

BREAK POINTS WON

Tiafoe – 5/8

Nadal – 2/6

Daniil Medvedev knows he has not performed to the best of his abilities at grand slams this season after his US Open title defence was ended by Nick Kyrgios.

Medvedev, who will also concede his spot at the top of the ATP's world rankings, has only won one of the four finals he has reached in 2022.

His record in the majors is a particular frustration for the 26-year-old. After losing to Rafael Nadal in the Australian Open final, Medvedev has reached the fourth round at Roland Garros and the same stage at Flushing Meadows, while The All England Club's ban on Russian and Belarusian athletes prevented him from competing at Wimbledon.

With Novak Djokovic unable to play in New York due to his COVID-19 vaccination status, Nadal, Carlos Alcaraz or Casper Ruud will become the world number one after the US Open's conclusion on Sunday.

"I mean, now that you say it, I remember it," Medvedev said in a press conference when asked how it felt to give up the number one spot.

"That's not nice because honestly after such a match, when you lose in a grand slam... I'm trying to look good here, but I'm disappointed.

"[I'm] not going to cry in the room, but I'm a little bit disappointed. For a few days I'm going to be just a little bit sad, looking at my phone, my laptop or watching some series.

"Yeah, it was not the first thing on my mind walking after the match, saying, 'Damn, I will not be the world number one anymore' – I actually don't know which place I will be. Probably three or four. I guess Carlos will pass me. I don't know actually.

"But that's motivation, try to do better. Obviously it was the last slam of the year. I didn't do well enough. Didn't win in Australia when I had the chance. Didn't get the chance to play at Wimbledon.

"Roland Garros, lost in the fourth round. Here, fourth round. Yeah, I should do better, should get more points if I want to be world number one again."

Medvedev went down 7-6 (13-11) 3-6 6-3 6-2 to Kyrgios, who has a 4-1 winning record against the Russian.

Asked if he thought it was Wimbledon finalist Kyrgios' best display against him, Medvedev suggested the Australian came close to replicating the form of greats Nadal and Djokovic.

"Yeah, it was a high-level match," he said. "[I] played Novak, Rafa. They all play amazing. Nick played kind of their level, in my opinion.

"He has a little bit different game because he's not a grinder in a way, [but] at the same time he can rally. He's tough to play.

"He has an amazing serve. He plays well, has every shot. It was a really high-level match from him.

"If he plays like this until the end of the tournament, he has all the chances to win it, but he's going to get tough opponents."

Nick Kyrgios took the opportunity to discuss the low points of his career after his victory over Daniil Medvedev, admitting he never thought he would have the chance to return to his best form.

Kyrgios conceded just one set to Medvedev in the 7-6 (13-11) 3-6 6-3 6-2 triumph at the US Open on Sunday.

It appeared during the first set tiebreaker that he was on the verge of one of his famous meltdowns, with a couple of racket slams and plenty of abuse towards his own box, but he steadied and fought back after a poor second frame.

Speaking to the media after the match, Kyrgios admitted the tiebreaker was do-or-die, saying: "I feel like if he'd got that first set, it was going to be pretty much an impossible task for me to come back and win."

This year's Wimbledon runner-up was humble and respectful when discussing the talent of Medvedev, and despite his muted celebration, highlighted what a big deal it is for him to perform well under the bright lights in New York.

"I didn't over-celebrate. It's only the fourth round, I've got quarter-finals [next]," Kyrgios said. "But it was an amazing experience obviously taking down the number one player in the world on Arthur Ashe Stadium.

"I don't really like to celebrate too much after that because I know that if I played him nine more times, he's probably getting on top of me the majority of the time.

"I hadn't won a match on Ashe before this week, now I've won two against two quality opponents, and I feel like I've been able to showcase [my talent].

"There's a lot of celebrities here, a lot of important people here watching. I wanted to get on that court and show them I am able to put my head down and play and win these big matches.

"For the tennis world I think it's important as well. People were really starting to doubt my ability to pull out matches like this at majors. I'm really proud of myself honestly because it hasn't been easy dealing with all the criticism."

Kyrgios continued to discuss how he feels he is perceived by the public and the media, saying it was more a feeling of relief than ecstasy when he finished the job.

"I feel like I'm more just proud of the way that I've bounced back after everything, honestly," he said. "I've been in some really tough situations mentally, and in some really scary places.

"Obviously if you look at it on paper, I probably wasn't expected to win that match. Maybe take a set or two if I'm lucky, give the people a show.

"It's a great win, but I come off the court and I'm just almost relieved that it's over because there's just so much pressure every time I go out on court, so much expectation, so much unpredictability of what I can do.

"I just sit there in the locker room after and I'm just super proud of the performance, because there was really a time where I didn't think I was capable of producing and doing this any more.

"I guess I'm just more relieved, and I'm super proud."

Nick Kyrgios is through to the quarter-final after a terrific 7-6 (11-13) 3-6 6-3 6-2 win over world number one and reigning US Open champion Daniil Medvedev.

It was a match that had all of the usual Kyrgios antics as he seemed to lose his cool during the first set tiebreaker, slamming his racket multiple times while repeatedly yelling at members of his entourage.

But he was able to work his way through it, saving three set points, before sealing the opening frame in 64 minutes with his fourth set point. Kyrgios relied on his dominant serve and limiting his errors, with just one double fault and 11 unforced errors with 21 winners.

The momentum from winning the set kept Kyrgios from spiralling mentally, but he became sloppy in the second, committing four double faults with only three aces, and he had 12 unforced errors with seven winners. It was the only set he had more than one double fault and more unforced errors than winners.

Zverev's ability to return in the second set was the difference, lifting his return point success rate from 33 per cent in the opener to 48 per cent to break twice and even up the match.

It had all the makings of a Kyrgios meltdown, but where he would usually begin to unravel and force desperate power shots to shorten points, he instead settled into the battle and refocused on getting into the net.

After only going to the net five times in the second set, he tripled that in the third, winning nine-of-15 attempts while not allowing a single break point opportunity. Kyrgios only created one break point chance for himself, and he took it with both hands to go up two sets to one.

In the fourth, Kyrgios was able to break again with his first opportunity early on, and with his serve switched on and firing he would only allow one chance for Zverev to break back, but he snuffed it out before going on to secure a second break and the victory.

Of their five career meetings, Kyrgios has now won four, and he will now get the benefit of the number one seed's path through the tournament. Next up, he will face 27th seed Karen Khachanov in the quarter-final as he searches for his first career grand slam title.

Data Slam: Kyrgios accomplishes feat not seen since 1987

Kyrgios is the first player since 1987 to defeat the world number one twice in the same year, with Australian compatriot Pat Cash the last to do it.

It is also the first time an Australian has defeated a world number one in a grand slam since Kyrgios himself, back in 2014 as a 19-year-old against Rafael Nadal at Wimbledon.

ACES/DOUBLE FAULTS

Kyrgios – 21/7

Medvedev – 22/2

WINNERS/UNFORCED ERRORS

Kyrgios – 53/38

Medvedev – 49/19

BREAK POINTS WON

Kyrgios – 5/7

Medvedev – 3/8