Daniil Medvedev and Stefanos Tsitsipas survived three-set scares at the National Bank Open on Tuesday, but five-time tournament champion Rafael Nadal departed Toronto without even taking the court. 

Top seed Medvedev, who won just three games against Nadal in the final in 2019, the last time the tournament was played, prevailed 4-6 6-3 6-4 in his opener against Alexander Bublik.

The man Nadal beat to win the title the previous year, Tsitsipas, failed to convert on five match points in an epic second-set tiebreak but recovered to down Ugo Humbert 6-3 6-7 (13-15) 6-1.

Nadal pulled out ahead of a scheduled match against Lloyd Harris, who beat him last week in Washington as the 20-time grand slam winner struggled with a foot injury. 

Countryman Feliciano Lopez replaces Nadal in the draw and will face Harris on Wednesday. 

Elsewhere Tuesday, sixth seed Casper Ruud needed more than two hours to put away Marin Cilic 6-3 3-6 6-3, while 14th seed Grigor Dimitrov suffered a quick 6-3 6-4 exit against big-serving American Reilly Opelka.

A pair of unseeded veterans advanced, with 2016 finalist Kei Nishikori a 6-4 6-7 (5-7) 6-2 winner over Miomir Kecmanovic and John Isner defeating Alejandro Davidovich Fokini 6-4 6-1 in just over an hour.

Two days after appearing in his first ATP Tour final at the Citi Open, Mackenzie McDonald fell 6-3 6-4 to Benoit Paire in his Toronto opener. 

In other first-round matches, Karen Khachanov beat Cameron Norrie 6-4 5-7 6-4, Frances Tiafoe downed Yoshihito Nishioka 6-4 6-3, Dusan Lajovic handled Emil Ruusuvuori 3-6 6-3 6-3 and Nikoloz Basilashvili defeated Jenson Brooksby 2-6 6-0 6-4.

Carlos Alcaraz, a 17-year-old wildcard, will face Rafael Nadal in the second round of the Madrid Open, with the top seeds set to get their campaigns underway on Tuesday and Wednesday.

Alcaraz, featuring in an ATP Masters 1000 event for just the second time, was in impressive form as he saw off France's Adrian Mannarino 6-4 6-0.

The teenager, who will face Nadal on his 18th birthday on Wednesday, fired 19 winners as he took the initiative against his more experienced opponent and his reward is significant.

He became the tournament's youngest ever match winner, beating the record set by Nadal.

"For me, [to] play against Rafa is a dream come true," Alcaraz said as he readies himself to go up against the 20-time grand slam winner.

"Since I was a kid, I wished to play a match against Rafa and now I will be able to here [on] the Centre Court of La Caja Magica in Madrid. It is a really special match against Rafa."

He told Tennis Channel: "It's the best present for my birthday."

The biggest casualty of the day was 13th seed Grigor Dimitrov, who lost 3-6 6-3 7-6 (7-5) to Lloyd Harris early on, the South African now 4-0 against top-20 opponents this year.

Two qualifiers in Pablo Andujar and Marcos Giron played out a remarkable encounter that lasted three hours and 21 minutes.

The first set alone clocked in at just over an hour and a half, but eventually Giron came through the gruelling clash 6-7 (8-10) 7-6 (7-4) 7-5 to set up a meeting with third seed Dominic Thiem.

Fabio Fognini defeated Carlos Taberner 7-6 (7-4) 2-6 6-3 for the right to face eighth seed and Italian countryman Matteo Berrettini.

Diego Schwartzman, the seventh seed, awaits Aslan Karatsev after he beat Ugo Humbert in straight sets in what was the Russian's debut appearance at the tournament.

Dan Evans and John Isner were among the other players to secure progress on Monday.

Novak Djokovic admitted he played an "awful" match against Dan Evans at the Monte Carlo Masters as Rafael Nadal advanced with ease to the quarter-finals.

World number one Djokovic, playing in his first tournament since winning a ninth Australian Open in February, suffered his first defeat of 2021 on Thursday.

Evans, who had never before reached the last eight of a Masters 1000 tournament, won 6-4 7-5 with a performance that belied his relative lack of success on clay.

The 30-year-old Briton will now meet David Goffin, who surprised fifth seed Alexander Zverev 6-4 7-6 (9-7).

"To be honest, this has been probably one of the worst matches and performances from my side I can recall in the last years," said Djokovic. "I don't want to take anything away from his win, but from my side, I just felt awful on the court overall. Just nothing worked. It's one of those days."

Saying he felt "completely the opposite" to Wednesday's win over Jannik Sinner, Djokovic added: "Just was obviously very, very windy, tough to play in these kinds of conditions against a guy like Evans who makes you move. He's very unpredictable with his shots. He dismantled my game."

Eleven-time Monte Carlo champion Nadal had no such problems in his match as he dismissed Grigor Dimitrov 6-1 6-1 in 55 minutes.

Nadal, who boasts a 14-1 career record against the Bulgarian, did not face a break point in either set against his off-colour opponent.

Dimitrov started the match with three double faults in his opening service game and was 4-0 down in each set.

"[I am] sorry for him. He played a bad match. That is the truth," said Spaniard Nadal. "He made a lot of mistakes. I was there. I was doing the right thing, but it is true that today was more his fault than my good tennis."

Nadal will face Andrey Rublev after the Russian battled past Roberto Bautista-Agut 7-6 (7-2) 5-7 6-3.

Stefanos Tsitsipas, who beat Cristian Garin 6-3 6-4, will face Alejandro Davidovich Fokina next, while Fabio Fognini's straight-sets win over Filip Krajinovic set up a meeting with Casper Ruud.

Rafael Nadal's bid to win a 12th Monte Carlo Masters title got off to an emphatic start as the Spaniard swept Federico Delbonis aside after Novak Djokovic had also booked his passage to the third round.

Nadal, 34, has won the competition more times than anyone else in its history and looked in good shape as he returned to the court for the first time since losing to Stefano Tsitsipas in the Australian Open quarter-finals on February 17.

He needed just 81 minutes to get past the Argentinian qualifier 6-1 6-2 as he improved his record in the tournament to 72-5, breaking Delbonis' serve five times and only dropping his own once.

He is not getting carried away, however, with Grigor Dimitrov likely to provide a sterner test in the next round after beating Jeremy Chardy 7-6 (7-3) 6-4.

"It was solid match, I think. Of course, a very positive result. He's a good player on clay. [It was a] positive start for me," Nadal said in his post-match interview.

"I think I just really played a solid match. Nothing unbelievable, but nothing wrong. Just a solid match, a positive start. I think I did what I had to do."

On Dimitrov, Nadal added: "We've had some great matches. In Melbourne, of course... we played another great match in Beijing, another one in Shanghai. He's a good friend, a good guy, and a great player. It's going to be a tough test in my second round.

"It's going to be his third. I need to be ready for it. I hope to be ready for it. I am just excited to play a tough match very early in the tournament."

A little earlier in the day, world number one Djokovic was in a similarly unforgiving mood as he overcame the potentially tricky obstacle of Jannik Sinner, the Serbian and two-time Monte Carlo champion winning 6-4 6-2.

Like Nadal, Djokovic was back in action for the first time since the Australian Open – which he won – and appeared fresh as he gave the promising young Italian something of a lesson in game management, reaching 10 matches unbeaten at the start of a season for the sixth time.

"It feels great [to be back and] also playing in Monaco, where I reside," Djokovic said. "I have used this club as a training base for almost 15 years, so it feels like playing at home."

Despite the rather commanding nature of his win, Djokovic was keen to pay tribute to the 19-year-old Sinner, adding: "It was a very good encounter. I thought it was a great first match [and] a big challenge for me. Jannik is in form. He played the final [in] Miami and has been playing well. I just hung in there today and managed to find the right shots and the right game at the right time.

"He has got a lot of talent and he has proven that he is the future of our sport. Actually, he is already the present of our sport. He played a final [in an] ATP Masters 1000 [tournament] already. He is making big strides in professional tennis."

Dan Evans awaits Djokovic after an impressive 6-4 6-1 win over Miami champion Hubert Hurkacz, while Alexander Zverez and Andrey Rublev – the fifth and sixth seeds – moved into the next round with respective straight-set victories over Lorenzo Sonego and Salvatore Caruso.

There were mixed fortunes for the other two top-10 seeds in action on Wednesday, as Pablo Carreno-Busta defeated Karen Khachanov 6-2 6-3, but Diego Schwartzman was sent packing by Casper Ruud, the Norwegian winning 6-3 6-3.

Novak Djokovic will tackle teenage rising star Jannik Sinner for the first time in a tantalising clash of tennis generations on Wednesday at the Monte Carlo Masters.

World number one Djokovic is returning to action this week, having taken time away from the tour since banking an 18th grand slam title by winning the Australian Open in February.

He received a first-round bye, but waiting for him in the last 32 is Sinner, who on Tuesday saw off 2017 Monte Carlo runner-up Albert Ramos-Vinolas 6-3 6-4, again illustrating the 19-year-old Italian's great potential.

World number 22 Sinner is the only teenager ranked inside the top 80 in the men's game and is coming off his first run to a Masters final, at the Miami Open.

The switch from hard courts to clay is one that Sinner is having to deal with, and seeing off a specialist on the surface in round one represents an impressive start, although facing two-time former champion Djokovic will be a step up.

"It's always good for me to see what I can do on clay," Sinner said, quoted on the ATP website. "Obviously, I am not in the best form on clay now for the first week.

"But I think today was a solid match from my side. It was not easy. He's not giving [away] one point, so you have to stay there the whole match. I think I played a good match from my side."

Greek fourth seed Stefanos Tsitsipas reached the last 16 with a 6-3 6-4 win over Russian Aslan Karatsev, but there was disappointment at the same stage for Italian eighth seed Matteo Berrettini, beaten 7-5 6-3 by Spain's Alejandro Davidovich Fokina. Those were the only second-round matches of the day.

Surprise Miami champion Hubert Hurkacz made a winning start, battling to a 6-3 3-6 6-3 first-round success against Italian qualifier Thomas Fabbiano to reach round two.

Roberto Bautista Agut, Grigor Dimitrov, Pablo Carreno Busta and Fabio Fognini each booked places in round two thanks to straight-sets wins.

Qualifier Federico Delbonis was a 7-5 6-1 victor over France's Adrian Mannarino, meaning the Argentinian faces the ultimate test in clay-court tennis next, a tussle with Rafael Nadal, the 11-time former champion in Monte Carlo.

Nadal has won all four of their previous matches, and their fifth encounter will immediately follow the Djokovic-Sinner match on Wednesday.

Third seed Alexander Zverev was sensationally dumped out of the Miami Open second round as Finnish 21-year-old Emil Ruusuvuori claimed his second top 10 win of his career.

Russuvuori bounced back after losing the first set, changing his tactics and overwhelming the German on Friday to set up a third round meeting with Mikael Ymer.

Ninth seed Grigor Dimitrov also bowed out, going down to Briton Cameron Norrie, while eighth seed David Goffin lost to James Duckworth.

World number two and top seed Daniil Medvedev eased past Lu Yen-hsun, while 11th seed Felix Auger-Aliassime, Karen Khachanov and John Isner all progressed.

TURNAROUND STUNS THIRD SEED

Zverev may have won last week's Mexican Open and the opening set 6-1 against Ruusuvuori but the tables turned quickly as the Finn produced one of the best displays of his career to date.

The 83rd ranked Finn moved regularly to the net and was aggressive in his approach, leaving Zverev rattled before winning 1-6 6-3 6-1 in a stunning momentum shift.

"I don't even know myself," Ruusuvuori said in his on-court interview when asked how he turned the match around.

"I wasn't feeling very comfortable in the first set and I was making a lot of unforced errors but slowly in the second I was starting to feel a bit better... Of course, it's one of the biggest wins in my career so it feels good."

He'll next face Ymer who knocked out 27th seed Nikoloz Basilashvili.

NINTH SEED BUNDLED OUT

Former world number three Dimitrov was ousted from the Miami Open on Friday, losing 7-5 7-5 to 56th ranked Norrie.

The Bulgarian took an early break and served for the first set at 5-3 but Norrie showed his mettle to break back twice to take the opener.

Norrie sent down 10 aces and was strong on serve throughout, claiming a significant win for his burgeoning career.

“It’s huge,” Norrie said. “He’s had a good start to the year. It was such a physical match at the start. He came out really fast and he set the tone at the beginning of the match. Massive one for me and I take a lot of confidence from it.”

Norrie's win sets up a third round meeting with American Taylor Fritz who beat Marcos Giron 6-2 6-2.

DANIIL DOMINATES, GOFFIN SHOCK

Australian Open runner-up Medvedev made light work of Lu, winning 6-2 6-2 to book a third round match with Australian 21-year-old Alexei Popyrin.

Medvedev won in less than an hour, hitting 24 winners and nine aces and making few errors in a clinical display.

Canadian 11th seed Aliassime proved too good for Pierre-Hugues Herbert 6-4 6-4, setting up a third round meeting with 18th seed John Isner who got past qualifier Mackenzie McDonald.

Seventh seed Roberto Bautista Agut progressed by virtue of a walkover against Lloyd Harris who had a wrist issue.

Eighth seed Goffin lost to world number 104 Duckworth 6-3 6-1 in a boilover.

Vasek Pospisil launched a stunning tirade during his three-set defeat to American qualifier Mackenzie McDonald in the first round of the Miami Open on Wednesday.

The Canadian former world number 25 was docked a point for verbal abuse, subsequently conceding the first set, before a meltdown during the change of ends.

Pospisil used a profanity in reference to ATP chairman Andrea Gaudenzi when speaking to chair umpire Arnaud Gabas.

“[Gaudenzi was] screaming at me in a player meeting for trying to unite the players — for an hour and a half," Pospisil said to Gabas. "If you want to default me, I’ll gladly sue this whole organisation.”

He did fight back to win the second set but ultimately lost to McDonald 6-3 4-6 6-3.

Pospisil, who is nowadays ranked 67th, was joined among the first-round exits by last week's Mexican Open semi-finalist Dominik Koepfer, who went down 6-1 6-4 to wildcard Hugo Gaston as he claimed his first career Masters 1000 win.

Sam Querrey, ranked 63rd, also bowed out 6-3 6-4 to Lu Yen-hsun, who will meet world number two Daniil Medvedev in the second round.

YOUNGSTER BEATS VETERAN

Australian youngster Alexei Popyrin secured his maiden win at the Miami Open, knocking out the oldest player in the draw Feliciano Lopez 6-4 7-6 (7-4).

Popyrin, 21, claimed his first ATP Tour title last month in Singapore and backed that up with a strong display against the 39-year-old former top 20 Spaniard.

Recent Open 13 Marseille runner-up Pierre-Hugues Herbert got past Portugal's Pedro Sousa 6-1 6-3, while South Africa's Lloyd Harris defeated Emilio Nava 6-4 7-6 (9-7).

Frances Tiafoe won in the final match of Wednesday, coming from behind to beat Stefano Travaglia 5-7 6-4 6-2.

COMEBACK CAM

Brit Cameron Norrie produced a heroic final-set fightback to claim his spot in the second round, where he will face Grigor Dimitrov.

Norrie trailed 5-1 in the third set against Yoshihito Nishioka, before winning 6-1 3-6 7-5, winning the last six games to clinch victory.

The 56th-ranked Brit sent down eight aces in the victory, although he got the edge on return and converted seven of his 10 break points.

SECOND ROUND

Top seed Medvedev will face Lu on Thursday, while third seed Alexander Zverev will take on Finland's Emil Ruusuvuori.

Norrie will meet Dimitrov, while 11th seed Felix Auger-Aliassime faces Herbert and eighth seed David Goffin will take on James Duckworth.

Harris has a match-up against seventh seed Roberto Bautista Agut.

Top seed Stefanos Tsitsipas was made to sweat but got past Felix Auger-Aliassime in three sets to reach the Mexican Open semi-finals on Thursday.

World number five Tsitsipas, who was a semi-finalist at last month's Australian Open, defeated seventh seed Auger-Aliassime 7-5 4-6 6-3 in Acapulco.

In a tight contest, back-to-back double faults from Canadian sensation Auger-Aliassime in the eighth game of the third set proved costly as Tsitsipas broke after the pair had held serve throughout the last.

"It got really tight," Tsitsipas said in his post-game interview. "I got a bit lucky with the double faults towards the end of the match.

"I was just persistent. Towards the end I had zoned in 100 per cent. Both of us brought an amazing energy out on the court. Felix is someone I've played a lot and I have huge respect for him."

Greek star Tsitsipas will next play emerging Italian teenager Lorenzo Musetti for a spot in the ATP 500 tournament decider.

Qualifier Musetti, who upstaged third seed Diego Schwartzman in the first round, stunned fifth seed Grigor Dimitrov 6-4 7-6 (7-3) in the final match of the day.

The 19-year-old Musetti will now contest his maiden ATP 500-level semi-final as he prepares to enter the top 100 on the men's tour after just his fourth main-draw appearance.

Alexander Zverev – the German second seed – progressed to the semi-finals with a walkover after eighth seed Casper Ruud withdrew due to a wrist injury sustained in practice.

Zverev will play countryman Dominik Koepfer in the final four after he defeated Cameron Norrie 7-5 6-4, maintaining his run of not dropping a set all tournament.

Top seed Stefanos Tsitsipas and fellow star Alexander Zverev progressed to the Mexican Open quarter-finals on Wednesday, but Milos Raonic bowed out.

Tsitsipas was too good for big-serving American John Isner in a 6-3 6-2 victory in Acapulco midweek.

A two-time Australian Open finalist, having also reached the French Open final four last year, Tsitsipas excelled on serve against Isner.

Greek star Tsitsipas only dropped one point on his first serve – not facing a break point throughout the last-16 contest – while firing down eight aces.

Standing in the way of Tsitsipas and a semi-final spot at the ATP 500 tournament is Canadian sensation Felix Auger-Aliassime.

In a battle of the NextGen, seventh seed Auger-Aliassime saved four of five break points in a 6-3 6-4 win over wild card Sebastian Korda.

Zverev will feature in his third Mexican Open quarter-final in four years after the second seed took down Laslo Djere 6-4 6-3.

Runner-up in 2019, Zverev will next face eighth seed Casper Ruud – who topped Tallon Griekspoor 4-6 6-3 7-6 (7-3) in the quarters.

"I think today what showed the most is that I got better with the match," Zverev said. "I started off extremely sloppy, started off with a lot of unforced errors.

"The longer the match went on the better I started playing and this is something that is very important for me. When I get into a rhythm I feel very comfortable on court and that's how I felt today."

Elsewhere, Lorenzo Musetti's giant-slaying run continued following a 2-6 6-3 7-6 (7-1) victory against Frances Tiafoe.

Musetti earned his first ATP 500 quarter-final as the Italian prepares to meet fifth seed Grigor Dimitrov, who eased past Miomir Kecmanovic 6-4 6-2.

There was an upset after fourth seed Raonic crashed out 6-4 6-2 at the hands of Dominik Koepfer, while sixth seed Fabio Fognini lost 6-4 6-3 against Cameron Norrie.

Italian qualifier Lorenzo Musetti may be ranked 120th in the world but he claimed his maiden top-10 scalp on Tuesday, beating Diego Schwartzman in the first round of the Mexican Open.

Musetti, the Australian Open boys' singles champion in 2019, secured a 6-3 2-6 6-4 win over ninth-ranked Schwartzman in a stunning success.

"There is a lot of work, a lot of sacrifice and I think some tears left in my eyes," the 19-year-old said during his on-court interview.

"I'm really proud of myself, but now I'm going to work harder and focus on the next days."

Musetti, whose forehand was excellent, defeated both Stan Wawrinka and Kei Nishikori at the Internazionali d'Italia in Rome last year.

Top seed Stefanos Tsitsipas had no such trouble, easing into the second round, where he will face big-serving American John Isner.

The Greek world number five beat France's Benoit Paire 6-3 6-1, aided by a strong display on serve.

"I didn't know what to expect from Benoit today," Tsitsipas said. "I think it's kind of tricky playing a tournament you haven't played before."

On facing 27th-ranked Isner next up, Tsitsipas added: "He's a guy that serves really well so that's going to be the biggest element and the one thing that I'll really have to resolve during that match."

Fourth seed Milos Raonic sent down 13 aces as he defeated American Tommy Paul 7-6 (8-6) 6-4.

In the late match, fifth seed Grigor Dimitrov got past Adrian Mannarino, who retired when trailing 6-4 3-0.

Serena Williams showed there would be no letting up in her relentless pursuit of tennis history as she hit the practice courts with one of the biggest names on the men's tour.

A semi-final defeat to Naomi Osaka at the Australian Open was the latest blow for Williams in her attempt to match Margaret Court's record of 24 grand slam titles.

Stuck on 23 since winning at Melbourne Park in 2017, Williams has gone repeatedly close in the subsequent years without getting her hands on a major trophy.

She took to the courts with Bulgarian ace Grigor Dimitrov, a beaten quarter-finalist in Australia and former world number three, as part of her continuing bid to keep improving and stay focused on those title goals.

Dimitrov could not resist boasting about the prowess of the player he was hitting with, posting a video of their session and writing on Instagram: "My practice partner is better than yours."

He added a goat emoji, signalling his belief that Williams is the greatest of all time.

Williams gestured a fond goodbye to the Australian Open crowds after her loss to Osaka, and became tearful in an after-match news conference when asked if it was a final farewell.

"I don't know. If I ever say farewell, I wouldn't tell anyone," said the 39-year-old.

Her next appearance on tour is expected to be at the Miami Open, starting on March 23, a tournament which has confirmed Williams, Osaka, Bianca Andreescu and Simona Halep among its field.

There was a little sibling envy from Venus Williams on Sunday when she questioned where Serena and Dimitrov were rallying.

"Omg are you guys hitting now? Where is my invite??" Venus wrote.

The next grand slam on the calendar is the French Open, beginning on May 23, while Serena may see Wimbledon, beginning on June 28, as providing her best chance of another slam.

She has won seven times at the All England Club, two behind the record held by Martina Navratilova.

Aslan Karatsev said finding stability off the court has helped him become the revelation of this year's Australian Open after the qualifier marched on to the semi-finals.

The Russian became the first qualifier to reach the last four of a major since Vladimir Voltchkov, famously in borrowed shorts, did so in 2000 at Wimbledon.

It was Pete Sampras who eventually blew away Voltchkov's threat at the All England Club on his way to another title.

And it turns out there is a connection between Karatsev and Voltchkov, with both men now calling Minsk their home.

But whereas Voltchkov is Minsk born and bred, Karatsev has taken a roundabout route to setting down roots in the capital of Belarus.

He explained on Tuesday how he was born in the Russian city of Vladikavkaz before moving as a toddler to Israel with his family and living there until the age of 12, when he and his father returned to Russia, spending time in the city of Taganrog.

Tennis took him to training bases in Moscow, then Halle in Germany, Barcelona, and finally Minsk.

It is in Minsk that Karatsev has linked up with former ATP professional Yahor Yatsyk, a man only one year his senior but already settling into coaching.

As Grigor Dimitrov succumbed to injury and slid to a four-set defeat against Karatsev on Tuesday, the unlikely figure in the final four reflected on his long road to this point.

"Yes, I was moving I would say too much," Karatsev said of his nomadic existence.

"In the end I found a coach, Yahor Yatsyk, and this is the right guy for me. He's helped me a lot, more the mental part, and then of course there is the technical stuff as well.

"I like to work with him. We're living in Minsk. We're practicing there."

Karatsev is the lowest-ranked man to reach a grand slam semi-final since Goran Ivanisevic, who won Wimbledon in 2001 on a wildcard entry while ranked 125th in the world.

His charge through the draw makes him only the second qualifier to advance to the Australian Open last four, after Bob Giltinan in December 1977.

"Of course it's amazing that I passed to the semi-finals from qualifying," Karatsev said. "I'm just trying to enjoy the moment and not thinking about that too much and playing from round to round."

He and Yatsyk set the goal of reaching the top 100, which Karatsev had not managed before getting to Melbourne.

Before this fortnight he stood at 114th in the rankings, but he will hurtle to a double-digit ranking next week.

"I think the key is to find the right team, the right coach that I found. I was really lucky to find him," Karatsev said.

"We just met in one tournament. We were saying, 'Okay, let's try to work together', and it's really a big luck that we started to work together and I have a good team around me."

Before he encountered Yatsyk, who as a player did not crack the top 1,000 in singles, Karatsev had a brief moment when he wondered if he might not make the grade.

"There was a time when I was injured that was a difficult time for me because I recovered after the injury, and then 2017 started, and I started to play again, and again I felt the knee," Karatsev said. "I said, 'Whoa.' I quit again for two and a half months, almost three, and I think this is the most difficult part."

Aslan Karatsev's Cinderella story and historic run continued after sensationally reaching the Australian Open semi-finals as Grigor Dimitrov struggled dramatically with injury on Tuesday.

Former world number three Dimitrov won the opening set and was on track to move through in Melbourne, but he faded alarmingly due to a lower back problem.

Karatsev capitalised to oust his much-more fancied opponent – who was barely able to walk afterwards – 2-6 6-4 6-1 6-2 on Rod Laver Arena, the Russian qualifier and world number 114 becoming the first man in the Open Era to reach the semi-finals on his grand slam debut.

The unheralded 27-year-old also became just the second qualifier to advance to the Australian Open last four after Bob Giltinan in December 1977 as defending champion Novak Djokovic or Alexander Zverev await.

Dimitrov was aiming to reach his second Australian Open semi-final and the final four of a slam for the fourth time in his career, and the Bulgarian star started well.

After being broken in the third game, 18th seed Dimitrov put the set back on serve immediately as he took control of proceedings.

Dimitrov fired down four aces, won 82 per cent of his first serves, hit six winners and made just five unforced errors, while Karatsev's unforced-error count hit 19.

But just as Dimitrov – who had not dropped a set en route to the quarters – looked like the man to beat, he wilted in remarkable scenes as Karatsev won the second set to level the match.

Dimitrov's first-serve winners dipped to 69 per cent – his second serve extremely problematic – while his unforced errors grew to 15 in the second set – and Karatsev took advantage.

The third set was a write-off for Dimitrov, who headed to the locker room for medical treatment after Karatsev cruised to a two-sets-to-love lead.

There were remarkable scenes in the third set, Dimitrov virtually conceding as he was unable to keep up with Karatsev due to the injury.

Dimitrov, who only won 12 points in the third set as he was unable to keep up with Karatsev or generate any power on his serve, emerged for the fourth set but, while he tried to will himself on, it only delayed the inevitable in sad scenes.

Data Slam: Karatsev joins Russian club
Karatsev became the fourth Russian man to reach the Australian Open semis in the Open Era, after Aleksandar Metreveli  (1972),  Yevgeny  Kafelnikov  (1999-2000)  and  Marat  Safin  (2002, 2004-05). He is also the lowest-ranked man to reach the semi-finals of a major since Goran Ivanisevic (125) at Wimbledon in 2001.

WINNERS/UNFORCED ERRORS
Dimitrov – 21/34
Karatsev – 34/44

ACES/DOUBLE FAULTS
Dimitrov – 9/7
Karatsev – 9/6

BREAK POINTS WON
Dimitrov – 4/14
Karatsev – 8/11 

Dominic Thiem's bid to reach back-to-back Australian Open finals was dashed by Grigor Dimitrov as the US Open champion surprisingly crashed out in the round of 16.

Thiem lost a thrilling final to Novak Djokovic in last year's Melbourne Park decider before breaking through for his maiden grand slam title at Flushing Meadows later in 2020.

But Thiem failed to secure another second-week berth in Melbourne, where the third seed was stunned 6-4 6-4 6-0 by former world number three Dimitrov on Sunday.

Thiem was aiming to reach the Australian Open quarter-finals for the second time and become the second Austrian man to feature in the quarters in Melbourne on multiple occasions after Thomas Muster (1989, 1994 and 1997).

The 27-year-old Thiem was also bidding to reach his ninth slam quarter-final and equal Muster's record for most major last-eight appearances by any Austrian – male or female.

However, Thiem – who rallied from two-sets-to-love down to top Nick Kyrgios in the previous round – was no match for Dimitrov behind closed doors on Rod Laver Arena amid a coronavirus lockdown in Victoria.

Both players hit 25 winners, but Dimitrov only tallied 18 unforced errors to Thiem's 41 following just over two hours on court.

Dimitrov progressed to his fourth Australian Open quarter-final, extending his record for most last-eight appearances at Melbourne Park by a Bulgarian player – man or woman.

An Australian Open semi-finalist in 2017, Dimitrov will now contest his sixth grand slam quarter-final – the 29-year-old is third for most quarter-final appearances by a Bulgarian player, behind Manuela Maleeva (nine) and Katerina Maleeva (seven).