Andrey Rublev was a surprise first-round loser at the Halle Open, while numerous seeds fell on the first day of the Queen's Club Championships.

Rublev came unstuck against Georgian Nikoloz Basilashvili, succumbing to a 7-6 (7-1) 6-4 loss as the world number eight crashed out in Germany.

Laslo Djere progressed after Henri Squire retired when 4-3 down, while sixth seed Pablo Carreno Busta secured a 6-3 7-6 (7-5) over French Open quarter-finalist Holger Rune.

Ugo Humber got the better of a topsy-turvy affair against qualifier Radu Albot, eventually triumphing 6-7 (4-7) 7-6 (7-4) 7-5 and Mackenzie McDonald defeated Marc-Andrea Huesler in straight sets.

Fourth favourite Taylor Fritz went down 6-3 6-3 against British wildcard Jack Draper, his first career win against a top-20 ranked player.

Reilly Opelka, the eighth seed, crashed out in the first round to New Zealand's Alex de Minaur, who claimed a straightforward 6-4 6-4 win.

Grigor Dimitrov, who won the event in 2014, battled past third seed Cameron Norrie 6-7 (2-7) 6-1 6-4, while Spaniard Alejandro Davidovich Fokina eased past compatriot Albert Ramos-Vinolas 7-5 6-4.

Alexander Bublik was 6-3 up before Italian Lorenzo Musetti retired, while seventh seed Marin Cilic capped the day's play in London by beating home hope Liam Broady 6-1 4-6 7-5.

Reigning Monte Carlo Masters champion Stefanos Tsitsipas will have to overcome Alexander Zverev if he is to have the chance to defend his title.

Zverev, who is ranked third in the world - two places higher than Tsitsipas - fought back to defeat Jannik Sinner 5-7 6-3 7-6 (7-5) in his quarter-final match, denying his opponent another top-five seed scalp following his prior win over Andrey Rublev.

"It means a lot, definitely, especially [with] how this year has been going so far for me," said Zverev after a gruelling three hours on court.

"I've lost long matches like that, so I’m happy I won this one."

Tsitsipas also orchestrated a superb turnaround against Diego Schwartzman, prevailing 6-2 6-7 (3-7) 6-4.

The Greek had looked set for a last-eight exit at four games down in the final set, only to stage a dramatic comeback to keep his hopes of a first title since last May's Lyon Open alive.

"There was a moment in the match where I felt what I was doing wasn't working," Tsitsipas said.

"He had a massive lead and momentum in what he was trying to do. I just tried to stay in the match as much as I could and that worked out very well.

"I wasn't expecting much at that point being a double break down, so I relaxed at that point."

Schwartzman meanwhile will rue his inability to put the tie to bed, having already reached two ATP finals this year.

Grigor Dimitrov and Alejandro Davidovich Fokina will face off in the other semi-final.

Bulgarian Dimitrov beat off Hubert Hurkacz in another final-set tie-break, winning 6-4 3-6 7-6 (7-2).

Fokina, who eliminated Novak Djokovic in the second round, turned over Indian Wells champion Taylor Fritz in another comeback result, triumphing 2-6 6-4 6-3.

Alexander Zverev and Stefanos Tsitsipas progressed to the quarter-finals of the Monte Carlo Masters with straight sets wins on Thursday, remaining on course for a final meeting.

Last year's runner-up Andrey Rublev, however, missed out on a last-eight spot after falling to a three-set defeat against Jannik Sinner.

World number three Zverev overcame Spain's Pablo Carreno Busta 6-2 7-5 to progress in Monaco, where he is seeking to win the sixth ATP 1000 title of his career.

"For the second clay-court match of the season, I can't complain too much," the 24-year-old second seed said on court after sealing the victory.

"Yes, I lost focus a little bit in the second set, but at the end of the day, he's somebody that can really play. I'm happy with a two-set win."

Tsitsipas (3) remains in contention for a second consecutive title in the principality after defeating Laslo Dere 7-5 7-6 (7-1) and will face off against 12th seed Diego Schwartzman for a semi-final spot after the Argentine defeated Lorenzo Musetti in a hard-fought three-set encounter.

There will be no repeat of 2021's final between Tsitsipas and Rublev, however, after the Russian fell to a thrilling 5-7 6-1 6-3 loss to ninth seed Sinner in the day's final contest.

The other seed to fall victim to a shock in the last 16 was world number seven Casper Ruud, losing 6-3 7-5 to Grigor Dimitrov, who will face Poland's Hubert Hurkacz in the last eight. 

Finally, Novak Djokovic's conqueror Alejandro Davidovich Fokina cruised past David Goffin 6-4 6-1 to set up a quarter-final tie with the United States' Taylor Fritz, who bested compatriot Sebastian Korda – with whom he played doubles with in Monte Carlo – in straight sets.

World number 18 Reilly Opelka is through to the semi-final of the US Men's Clay Court Championships in Houston after defeating qualifier Gijs Brouwer 6-3 7-5.

The giant American, who measures in at six-foot-11, was terrific in the opening set, winning 84 per cent of his successful first serves (16-19) and allowing no break point opportunities.

The second set was much more competitive, as Brouwer broke first to go up 3-1, but Opelka answered instantly and then grabbed the match-winning break when 6-5 up to avoid a tie-breaker.

Opelka will face a fresh Nick Kyrgios in the semi-final after the Australian was gifted a walkover win against Michael Mmoh due to injury.

In a clash between two top-five seeds, world number 29 Christian Garin got the better of world number 13 Taylor Fritz 6-2 6-7 (5-7) 6-3.

What made Garin successful in the first and third sets was his return game, winning more than half of his return points in those sets combined (26-51).

Fritz had chances to get back into the game, but Garin saved 11 of 14 break point opportunities, including six of seven in the deciding third set.

Garin will play American John Isner in the semi-final after Isner triumphed in a three-set battle against Frances Tiafoe 6-4 2-6 6-3.

Isner's trademark serve was inconsistent, and abandoned him in a grim second-set performance, winning just 11 of 21 service points on his way to getting broken twice to allow Tiafoe to force the match into a third frame.

In Isner's two successful sets, he won more than 80 per cent of his first serves (35-41), and allowed no break point opportunities in the third.

Taylor Fritz saw his way past Alejandro Tabilo to advance to the quarter-finals at the US Men's Clay Court Championships, winning 6-1 6-4 on Thursday.

Fresh off his maiden ATP 1000 title at Indian Wells and fourth-round run in Miami, the American world number 13 needed just 62 minutes to win in straight sets, in his first clay court match for the season.

Fritz's serve was not particularly secure, though, with the unseeded Tabilo converting on only one of six break point attempts. Fritz was more efficient and assertive when opportunities presented on the other hand, taking two of three break point chances on Tabilo's serve while winning 12 out of 19 points returning on his second serve.

Despite the Chilean world number 100 fighting back to 4-4 from 3-0 down in the second set, Fritz steadied to close out the match.

"I felt like tonight was going to be a really tough match, given he's done really well on clay," Fritz said post-match. "It was my first match [on clay]. I'm pretty happy with how I played. I can't complain, I got out of that pretty solid."

Fritz will now face another Chilean, fifth seed and defending champion Cristian Garin, who came back from a set down to defeat Jordan Thompson 3-6 6-3 6-3.

Entering the Houston event on a five-match losing streak, Garin has come from behind in back-to-back matches to win.

Sixth seed Frances Tiafoe also went the distance on Thursday, earning a 5-7 7-5 7-6 (7-4) win over Uruguayan Pablo Cuevas.

With neither garnering break point chances in the third set, Tiafoe finally created breathing room by winning four straight points at 2-2 in the deciding tie-break, before closing out the match.

It sets up an all-American quarter-final with John Isner, who defeated Steve Johnson 6-7 (1-7) 7-6 (7-4) 6-3 in Thursday's final game.

Emerging Spanish star Carlos Alcaraz continued his rise with a 7-5 6-3 upset of third seed Stefanos Tsitsipas to reach the Miami Masters quarter-finals on Tuesday.

The 18-year-old, who reached last year's US Open final eight after beating Tsitsipas in the third round, proved too good again for the Greek in one hour and 50 minutes.

Alcaraz reached last week's Indian Wells semi-finals and is now 15-2 on the season, with the win setting up a clash with Serbian Miomir Kecmanovic who upset last week's Indian Wells champion Taylor Fritz 3-6 6-1 6-4.

Tsitsipas broke the Spaniard in the sixth game and led 5-2 before Alcaraz reeled off seven straight games to sensationally take the first set.

Alcaraz surged ahead in the second set, with his defence and speed leaving Tsitsipas short on answers.

The Spaniard, who saved seven of eight break points throughout the match, converted his fourth match point for victory.

"It was really, really tough. He was playing unbelievable," Alcaraz said after the match. "All I can say is I fought until the last ball in the first set [to] come back."

Ninth seed Jannik Sinner won 7-6 (7-3) 6-3 over enigmatic Australian Nick Kyrgios, who had a furious outburst directed at umpire Carlos Bernardes.

The Australian was heard to label Bernardes "an absolute clown" and continued to berate the umpire late in the first set, leading to a code violation and two penalties.

Kyrgios completely lost his cool, demanding to speak to a tournament official before smashing his racquet early in the second set, leading to a game penalty as well.

Sinner will next take on Argentine Francisco Cerundolo after he defeated 28th seed Francis Tiafoe lost 6-7 (2-7) 7-6 (7-3) 6-2.

Top seed Daniil Medvedev made light work of Jenson Brooksby 7-5 6-1 to set up a quarter-final showdown with reigning champion Hubert Hurkacz who won 7-6 (7-3) 6-2 over Lloyd Harris. Medvedev will return to the top of the ATP rankings if he wins their quarter-final.

Second seed Alexander Zverev got past Thanasi Kokkinakis 6-4 6-4 and will meet sixth seed Casper Ruud in the last eight, after the Norwegian won 6-3 6-4 over Briton Cameron Norrie.

The Miami Masters' top seed, Daniil Medvedev, had no problems making his way past Spain's Pedro Martinez 6-3 6-4 to earn his spot in the fourth round.

Serving was the story of the match as the world number two tallied up 14 aces to his unseeded opponent's zero, and only allowed Martinez to see five second serves in the opening set, with Zverev winning all five. Overall, Zverev won 20 of 24 points on serve in the first set.

The second set was more competitive, with Martinez even breaking back after Zverev jumped ahead and looked to coast to victory, but he could not hold off the Russian down the stretch.

Medvedev will play American Jenson Brooksby in his fourth-round matchup after he won a hard-fought 6-3 5-7 6-4 struggle against 15 seed Roberto Bautista Agut.

In a razor-close contest, Brooksby was just slightly better throughout, winning 60 per cent of his service points compared to the Spaniard's 59 per cent, as well as winning 41 per cent of return points compared to Bautista Agut's 40 per cent.

Fresh off his Indian Wells Masters triumph over Rafael Nadal, Taylor Fritz kept his good form going with a 7-6 (7-2) 6-4 win against American compatriot Tommy Paul.

Fritz, who is now up to world number 13, did not have his serve broken all day, winning 81 per cent of his successful first serves (30-37), while also capitalising on the only two break points he saw.

14 seed Carlos Alcaraz only needed two sets to get past 21 seed Marin Cilic 6-4 6-4, creating nine break point opportunities to Cilic's one, which was saved.

In the late session, and in a meeting of rapidly rising prospects, 22-year-old Serbian Miomir Kecmanovic pulled off an upset 7-6 (7-4) 6-3 win over 21-year-old American Sebastian Korda.

Meanwhile, three seed Stefano Tsitsipas was too much for Australian Alex de Minaur, winning 6-4 6-3 after allowing no break point opportunities in the opening set, and saving all three in the second.

Rafael Nadal is facing new injury concerns, after Taylor Fritz ended his unbeaten streak for 2022 in the Indian Wells Masters final on Sunday.

Having to take a medical timeout during his win in the semi-final against countryman Carlos Alcaraz, the 35-year-old was forced into another injury break against Fritz, before losing 6-3 7-6 (7-5).

Nadal, whose 2021 was halted mid-year due to foot injury after back pain at the start of the season, ultimately rued his inability to fully compete against Fritz.

"I had pain, honestly. I had problems breathing," he said post-match. "I don't know if it's something on the rib, I don't know yet. When I'm breathing, when I'm moving it's like a needle all the time inside. I get dizzy a little bit because it's painful.

"It's a kind of pain that limits me a lot. It's not only about pain, I don't feel very well because [it] affects my breathing."

Nadal's 20-match unbeaten streak for 2022, which saw him claim the Australian Open and Acapulco titles in the process, also came to an end on Sunday. The world number four said the streak ending before coming into the clay season provides particular sadness.

"Honestly, I wanted to make it perfect before clay. [It] has been very, very, very beautiful," Nadal said.

"Honestly, I am sad because the way I was not able to compete. It's tough to have these feelings….but in the final it's very, very ugly. But in sport it's not about talking of the past, we need to talk about today. And today is a difficult day for me. "

Nadal commended Fritz on the victory, however. The 24-year-old claimed his maiden ATP 1000 title despite carrying an ankle injury.

According to the 21-time grand slam winner, it is a sign of things to come from the American, who had to back up from a tough win over Andrey Rublev in the semi-final on Saturday.

"Victories like today help. He played well. He went through some great matches during this week I think, especially yesterday," he said.

"A lot of credit to him on the victory of yesterday. In my opinion, his victory of yesterday is much bigger than his victory of today because he had [a] much tougher opponent in from yesterday.

"He already played great matches in Australia, this year if I'm not wrong, against [Stefanos] Tsitsipas.

"It's obvious that he is improving. With this victory, it's a great start of the season for him. He will have a chance to be very close if not in the top 10 very soon."

Taylor Fritz had never experienced "worse pain in my life before a match" before overcoming an ankle injury to end Rafael Nadal's winning start to the season and win the Indian Wells Masters on Sunday.

The American 20th seed, who has never been further than the fourth round at a major, claimed a breakthrough maiden ATP Masters 1000 title with a 6-3 7-6 (7-5) victory over Nadal in two hours and six minutes.

Fritz, 24, was not sure if he would be able to take his place in Sunday's decider after tweaking his ankle in Saturday's semi-final win over Andrey Rublev which he battled in the lead-up.

The injury was far from ideal preparation coming up against the Spanish fourth seed, who was on a 20-0 run to start 2022 having won January's Australian Open for a record-breaking 21st career major.

"I can't even begin to describe how ridiculous it is that I was able to play how I could play today," Fritz said during his post-match on-court interview. "I've never ever experienced worse pain in my life before a match.

"If I knew it was going to be that bad, I wouldn’t have come out here [beforehand] because I think people saw it. I took a couple of change-of-direction steps and screamed.

"I was trying to act tough as I had cameras on me. It probably looked like I was over-exaggerating the pain with how loud I screamed when I felt it.

"We did a lot of work leading up to the match. I went through a roller-coaster of emotions before the match, from thinking there's no way I could possibly play then to doing so much work on the ankle and going out again hitting on one of the backcourts and being really happy, thinking I can play.

"Really it didn’t affect me out on the court. Unbelievable."

California native Fritz, who reached last year's Indian Wells semi-finals, admitted winning the event was a "childhood dream" and that it did not feel real.

"I'm going to have to hold back tears for every single interview I do and every on-court speech," he said. "This is going to be tough. I'm such a happy crier.

"This is one of those childhood dreams, winning this tournament especially, you never thought would come true. I keep saying 'no way this is real'."

The title is the biggest of Fritz's career to date, triumphing in his first Masters 1000 final, and becoming the first American men's champion at Indian Wells since Andre Agassi in 2001.

Fritz is also the youngest male champion at the event since Novak Djokovic in 2011 and achieved that by ending Nadal's career-best 20-match win streak, denying him a record-tying 37th ATP Masters 1000 title too.

"I've lost these matches against the big guys my whole life," Fritz said. "It's always felt like they're unbeatable. To do it on the biggest stage, there's no other way. To win a big title, I feel like you've got to beat the best."

Taylor Fritz spectacularly claimed his first ATP 1000 trophy on Sunday, defeating Rafael Nadal 6-3 7-6 (7-5) to win the Indian Wells Masters.

Having only won once in his previous five finals, against Sam Querrey at Eastbourne in 2019, the 24-year-old displayed distinct maturity under pressure despite carrying an ankle injury.

The Spanish world number four's undefeated streak coming into Sunday's final ended at 20 with the loss.

For Fritz however, his first Masters title coming in as many finals was difficult to process, especially against an opponent in Nadal in front of his home crowd.

"I've lost these matches against the big guys my whole life," Fritz said in his on-court interview. "It's always felt like they're just unbeatable, so to do it on this stage, you have to beat the best."

"This is just one of those childhood dreams, winning this tournament especially at Indian Wells. This is one of those childhood dreams that you just never think will come true. I just keep saying 'no way this is real'."

Both faced pressure under their respective serves, but Nadal ultimately failed to capitalise on opportunies, converting only twice out of a possible 10 break points.

His 34 unforced errors in comparison to Fritz's 22, in such a closely contested match, contributed to the eventual result.

Fritz overcame his ankle concerns to race to a 4-0 lead in the first set before Nadal, facing his own physical challenges, took a medical time-out after losing the first set.

Nadal saved a championship point to force a tiebreak in the second set. Reflecting the pressure he was under after going down a mini-break, though, the Spaniard's ground strokes teetered dangerously close to the baseline.

The 35-year-old even made rare approaches to the net to turn defence into attack, amid some thrilling exchanges from the baseline, but a scuffed volley from mid-court to set up another Fritz championship point was the last straw despite displaying his trademark doggedness.

Rafael Nadal extended his 2022 win streak to 20 matches and clinched a spot in his fifth Indian Wells Masters final after a thrilling three-set victory over compatriot Carlos Alcaraz on Saturday.

The fourth seed lifted in the final set to win 6-4 4-6 6-3 over 19th seed Alcaraz in three hours and 12 minutes, with Nadal to play American Taylor Fritz in Sunday's decider.

The match was played amid blustery conditions, particularly the second set, where debris flew on to the court regularly interrupting or delaying play, which appeared to impact Nadal more.

Alcaraz had more winners (41-24) but also more unforced errors (34-26), with Nadal finding another gear when it mattered in the final set.

Nadal's victory improved his record to 20-0 this season, earning him a fifth Indian Wells Masters final spot and his first since 2013. The Spaniard won the Indian Wells crown in 2007, 2009, 2013 and was runner-up in 2011.

The 35-year-old also clinched a berth in his 53rd Masters final, keeping him on track for a 37th title at this level. 

The 21-time major winner claimed the decisive break in the eighth game of the third set after a physio break for treatment on his back, before serving out to-love for victory.

"In the second, the conditions became crazy, honestly," Nadal said during his on-court interview. "It was not funny playing in this wind. In terms of tennis it was OK but in terms of stopping all the time, it was not good.

"In the third I think I played much better. I played much more aggressive. I am super happy. Being in the final means a lot to me."

Alcaraz had started the better to open up a 2-0 lead in the opening set, before Nadal responded emphatically.

There were five breaks in a row in the second set, including the Spanish teenager going ahead 5-4 after a game lasting almost 20 minutes, converting his seventh break point, before serving out the set.

As the conditions settled, Nadal showed more aggression, coming into the net with regularity before taking the key break in the eighth game.

American 20th seed Fritz reached his first ATP Masters 1000 final with a 7-5 6-4 victory over seventh seed Andrey Rublev in one hour and 50 minutes.

The California native is the first American male to reach the Indian Wells since John Isner in 2012.

"It's just unreal, really. It doesn't even seem real. I'm just trying to take in the moment, regroup and come back tomorrow for the final," Fritz said in his on-court interview. "But it's a dream come true."

"Today I definitely played my best match of the tournament so far. I was so much more aggressive from the ground and so much more solid [with] my ground strokes, whereas [in] other matches I was maybe playing a bit safer.

"I really tried to take it to him and impose my game today. I did it well, so that helped a lot."

Andrey Rublev made his fourth ATP Masters semi-final on Friday, dispatching Grigor Dimitrov in under 90 minutes at Indian Wells in a 7-5 6-2 win.

Dimitrov had only faced two break points for the tournament until this quarter-final, and Rublev capitalised when his opponent’s serve evaded him. Rublev was returning with particular focus, getting 85 per cent of points back across the court on Dimitrov's first serve alone.

Rublev broke in the fifth game of the first set on the back of two double faults, but Dimitrov secured one of his own with a trademark backhand pass. The 24-year-old Russian answered right back to regain breathing room and close out a tight first set.

Securing the break in the third game of the second, that consistent pressure on Dimitrov's serve again forced two double faults in the fifth game. From there at 4-1, Rublev saw the finish line.

The win was the seventh seed’s 13th in a row, adding Indian Wells to semi-final appearances at Miami, Monte Carlo and Cincinnati. A win in the final would equal a career-high 15 matches in a row undefeated.

"I think I played really well. In the beginning, it was more about who will be the first to dictate and play more aggressive, because both of us like to dictate with our forehand," Rublev said afterwards.

"The return [of serve] was one of the most important things. If you can bring as many returns as possible [into the court], and then here with these conditions, in some moments it's tough to serve."

In Friday's other quarter-final, Taylor Fritz did it tough against the unseeded Serbian Miomir Kecmanovic, winning 7-6 (7-5) 3-6 6-1.

While Kecmanovic was content playing defence and grinding from the baseline, Fritz was the more active and it was most apparent at 5-5 in the first set.

Down 0-30, Fritz stood and delivered from the middle of the baseline with a booming forehand, before securing a critical hold.

The difference in tactics showed in the eventual winner differential, with Fritz's 35 in comparison to Kecmanovic's 15. Despite Fritz's relatively low unforced error count, he still gifted Kecmanovic the second set, serving three consecutive double faults to surrender the break at 3-4.

He regrouped and reeled off the opening five games of the third set, setting up his semi-final with Rublev. The other semi-final will see Rafael Nadal and Carlos Alcaraz meet in an all-Spanish duel.

Rafael Nadal did it tough against Reilly Opelka on Wednesday, eventually winning his way through to the quarter-finals at the Indian Wells Masters.

Nadal displayed an abundance of tactical nous, nullifying the American’s big hitting and service game to emerge the 7-6(6-3) 7-6(7-5) winner.

Along with a 76 percent first-serve rate, Opelka hit more winners with 26 for the match, but the 35-year-old Spaniard was able to grind out points from the baseline with his trademark heavy topspin. As a result, Nadal’s winner/unforced error differential was +14 in comparison to Opelka’s +1.

"He is one of the toughest opponents on tour," Nadal said post-match. "It is very tough to control his weapons with his serve and forehand.

"I think I played my best match of the tournament so far today. I am very pleased with how I was able to win the match, with two difficult tie-breaks. This victory means a lot to me."

The highest ranked player left in the draw, Nadal will now face Nick Kyrgios, who progressed to the quarter-finals after Jannik Sinner withdrew with illness.

Matteo Berrettini made a shock exit, meanwhile, losing 6-3 6-7(5-7) 6-4 to unseeded Serbian Miomir Kecmanovic.

The Italian world number six was put under constant pressure, with Kecmanovic targeting his backhand and hovered the baseline to close the angles on serve.

The 22-year-old’s only other top 10 victory came against Alexander Zverev, also the world number six then, at Cincinnati in 2019. He will now face Taylor Fritz, who defeated Alex de Minaur 3-6 6-4 7-6(7-5).

Also on Wednesday, Grigor Dimitrov edged past John Isner 6-3 7-6(8-6). In his unique style, the Bulgarian 33rd seed came up with the shot of the day, flicking a forehand pass across the visibly stunned Isner.

He will face Andrey Rublev, who defeated Hurbert Hurkacz 7-6(7-5) 6-4. In Wednesday’s other results, Carlos Alcaraz Garfia comfortably defeated Gael Monfils 7-5 6-1, while Cameron Norrie accounted for Jenson Brooksby 6-2 6-4.

Matteo Berrettini survived a scare to eventually progress to the fourth round at the Indian Wells Masters on Tuesday.

The Italian sixth seed had to fight from 2-5 down in the second set and saved three set points, before powering through to triumph 6-4 7-5 over Lloyd Harris.

"I got a little bit nervous," Berrettini said post-match. “I didn’t like how I handled the start of the second set. I let the anger get out a little bit, which helped. I found the right balance in order to break him in the important moment and then I had the momentum.”

The world number six found another level in reeling off five straight games, and will now face unseeded Miomir Kecmanovic, who accounted for Botic van de Zandschulp 7-6(6-3) 7-5.

Taylor Fritz was also pushed by Spanish qualifier Jaume Munar, taking a third-set tiebreaker to progress to the fourth round.

The 20th-seeded was made to work for it in a match that lasted just under three hours, but Munar feel short in the clutch, with two unforced forehand errors in the closing tiebreak to give Fritz a three-point gap.

In Tuesday's last game, Andrey Rublev showed rare composure to progress past Frances Tiafoe 6-3 6-4. 

Neither got off to the best of starts, with Rublev and Tiafoe sharing service breaks in the opening four games of the first set. The characteristically volatile Rublev managed to regroup, though, and stayed calm even when Tiafoe got his home crowd on side. 

Despite a low 67 percent on first serve, Rublev won 83 percent of those points, while Tiafoe did himself no favours with an even lower 58 percent first-serve rate.

Last-year’s semi-finalist will face 29th-seeded Alex de Minaur, who defeated Tommy Paul 7-6(6-2) 6-4.

The Australian world no. 31 faced immediate difficulty on service, with only his second service game going to eight consecutive deuces, after five saved break points. He eventually saw the match through, after breaking for 4-3 in the second set.

Fellow seeds Hubert Hurkacz and Grigor Dimitrov both went through relatively unscathed, with respective wins over Steve Johnson and Alexander Bublik.

Dimitrov will face John Isner, who saw past Diego Schwartzman 7-5 6-3 in Tuesday’s other result.

Alexander Zverev saved two match points and battled back to salvage a dramatic victory over Jenson Brooksby at the Mexican Open in what was the latest finish in tennis history.

Second seed Zverev – the defending champion in Acapulco - wrapped up a dramatic win at 04:55 local time after his own lengthy contest had followed two other epic three-setters earlier on the schedule.

Zverev at one stage looked like he was on the way out but ultimately triumphed 3-6 7-6 (12-10) 6-2 to book a second-round tie against Peter Gojowczyk.

The German had beaten Brooksby in a match that also went to a decider when they clashed at Indian Wells in October and he was pushed to the limit again in a battle lasting 200 minutes.

Having dropped the first set, Zverev had to fend off three break points at 3-3 in the second and saved match points at 6-5 and 10-9 down as part of an epic tie-break that went in his favour. 

Zverev was then more comfortable as he broke twice in the decider to seal victory, his American opponent paying the price for converting just one of his seven break-point opportunities in a match that made history for its late finish.

The previous latest ATP finish time was Lleyton Hewitt's 2008 Australian Open clash with Marcos Baghdatis, which ended at 04:34 local time.

Elsewhere, Stefan Kozlov overcame cramps in the second set to outlast Bulgarian Grigor Dimitrov 7-6 (10-8) 5-7 6-3, with that match lasting three hours and 21 minutes.

John Isner sent down 29 aces and saved a match point as he trailed 5-2 in the third set, ultimately winning 7-5 6-7 (4-7) 7-6 (7-3) over veteran Fernando Verdasco in another epic topping the three-hour mark that helped to push back the start time for Zverev and Brooksby.

Seventh seed Taylor Fritz got past Frenchman Adrian Mannarino 6-3 6-3, while Dusan Lajovic knocked off Sebastian Korda 6-4 4-6 7-5 and eighth seed Pablo Carreno Busta beat Oscar Otte in straight sets.

At the Chile Open in Santiago, eighth seed Facundo Bagnis won 6-3 6-0 over Bernabe Zapata Miralles in the round of 32.

Brazilian Thiago Monteiro got past local Nicolas Jarry 7-6 (11-9) 6-4, while qualifier Juan Ignacio Londero and wildcard Thiago Seyboth Wild also progressed.