Dominic Thiem suffered defeat in his first ATP Tour match since June, losing at the Serbia Open to John Millman.

Thiem has been out of action since suffering a right wrist injury and the former world number three was able to claim the second set in his comeback match.

But he could not avoid a 6-3 3-6 6-4 defeat in a contest that lasted two hours and 35 minutes.

Speaking afterwards, Millman said: "It is great to be back here. I was looking forward to coming back and [playing]. All credit to Domi.

"I can't claim it was one of my biggest wins because he is just coming back from injury and I know how hard that is, coming back from three surgeries myself.

"I know it has been tough for Domi but the game is better having him back. Especially on this surface. I have got to take this win because when he gets better and fitter, it is going to be tough."

Next up for the Australian is Miomir Kecmanovic.

NextGen star Jiri Lehecka booked a meeting with second seed Andrey Rublev by beating Henri Laaksonen, while Filip Krajinovic overcame David Goffin.

At the Barcelona Open, fourth seed Cameron Norrie had to come back from a set down to see off Egor Gerasimov, though his 12th seeded fellow Briton Dan Evans lost to Lorenzo Musetti.

There were routine wins for second seed Casper Ruud, sixth seed Diego Schwartzman and 11th seed Lorenzo Sonego.

Cristian Garin was on the end of a shock thrashing by Denmark's Holger Rune in the first round of the Serbia Open on Monday.

The Chilean fifth seed, who was the highest-ranked player in action, is regarded as one of the ATP Tour's best on clay but hardly got a look-in as 18-year-old Rune emerged with an impressive 6-3 6-1 win.

Rune has risen to a career-high 72 in the ATP rankings and showed every sign that he will continue to climb over the season as he produced an aggressive performance that saw him take six of 17 break points.

Playing in only his fifth ATP Tour match on clay, Rune needed just an hour and 25 minutes to see off Garin – the winner of five tour-level titles on the surface – and set up a second-round clash with either Dusan Lajovic or Taro Daniel.

Sixth and seventh seeds Fabio Fognini and Miomir Kecmanovic avoided similar shocks, though their respective wins were wildly different.

Kecmanovic crushed veteran Richard Gasquet 6-0 6-3, while Fognini was forced to overturn a one-set deficit in his defeat of fellow Italian Marco Cecchinato 6-7 (5-7) 6-2 6-2.

No seeds were in action at the Barcelona Open, but Italian prospect Lorenzo Musetti enjoyed a hard-fought 7-5 7-5 defeat of Argentina's Sebastian Baez to seal his spot in the second round.

The 20-year-old is now 5-2 for the clay season and will go up against Dan Evans next. Joining Musetti in progressing is another promising youngster in Brandon Nakashima, who beat Nicolas Alvarez Varona 7-6 (8-6) 6-3 to tee up a clash with number two seed Casper Ruud.

Mackenzie McDonald, Elias Ymer, Kwon Soon-woo and Federico Coria were among the other victors, while retiring 2004 champion Tommy Robredo bowed out with a 6-1 6-1 loss to Bernabe Zapata Miralles.

Stefanos Tsitsipas defended his Monte Carlo Masters crown and lifted his eighth ATP Tour title by defeating Alejandro Davidovich Fokina in straight sets on Sunday.

Greek Tsitsipas, who defeated Andrey Rublev to triumph in Monaco last year, eased past second seed Alexander Zverev in the semi-final and repeated the trick with a 6-3 7-6 (7-3) victory over Davidovich Fokina.

The Spaniard beat Novak Djokovic and reigning Indian Wells Masters champion Taylor Fritz en route to his maiden ATP Tour final, and started well on Court Rainier III with an early break.

However, Tsitsipas found his rhythm with his ferocious forehand to break back before winning four of the next five games to take the lead.

The world number five, appearing in his fourth Masters 1000 final, then failed to serve out for the match at 5-4 up in the second set, but recovered in the tie-break to secure his first trophy of the season.

In doing so, Tsitsipas becomes the sixth player to manage consecutive Monte Carlo titles in the Open Era, while half of his eight tour-level titles have come on clay.

"I am very proud of myself," Tsitsipas said in his on-court interview. "Things weren't going well at one point, but I managed to stay composed to finish the match off.

"I am really proud with the belief I put in my game. Sometimes you doubt yourself, but it is always important to keep your head high."

Davidovich Fokina was aiming to become the first unseeded champion in Monte Carlo since Thomas Muster in 1992, and Tsitsipas acknowledged the 22-year-old made him fight to reclaim the trophy.

"He fought in moments I didn't expect him to fight," Tsitsipas said. "He can hit incredible winners out of nowhere and play unpredictably.

"But I was able to minimise that. I knew he would be a dangerous opponent but that is a great win for me. I think we will see great results from him in the future."

Stefanos Tsitsipas remains on course for a second consecutive Monte Carlo Masters title after recording a straight-sets semi-final win over Alexander Zverev.

The third seed, who defeated Andrey Rublev to clinch the title in Monaco last year, produced a scintillating performance to beat the world number three 6-4 6-2 in Saturday's last-four encounter.

Tsitsipas will face world number 46 Alejandro Davidovich Fokina in Sunday's final, and the Greek said he will need to perform at an even higher level to defeat the 22-year-old, whose incredible run continued with a three-set win over Grigor Dimitrov in the final four.

"It was good," Tstispas told Amazon Prime Video of his semi-final win. "I don't know whether the long match [his three-set quarter-final win over Diego Schwartzman on Friday] gave me some rhythm, but I was able to play good tennis today. I'm happy with the level I was able to execute, and I came up with some good ideas on the court.

"I'm looking forward to the next one, I have a difficult opponent tomorrow, so I need to be ready and to take the best out of this one and move on.

"It's going to take a little bit more [to beat Davidovich Fokina], he's in a good rhythm. I've played him before, and he's a difficult opponent, I'm going to be as ready as possible, he's definitely improved and I'm going to have to produce the best tennis I can."

Davidovich Fokina, who has made headlines by eliminating Novak Djokovic and Indian Wells Masters champion Taylor Fritz during a thrilling run in the municipality, beat Dimitrov 6-4 6-7 (2-7) 6-3 earlier on Saturday, reaching his first ATP Tour final.

The unseeded Spaniard needed two hours and 43 minutes to wrap up his semi-final contest, and revealed that a bathroom break allowed him to reset his mind and clinch a hard-fought victory after he failed to serve out the second set at 5-4 up.

"I am so happy to be in the final, it's a dream come true to try to have the title," he said after the win.

"When I was a kid, I was dreaming about this day and it's come true, I'm so happy.

"In the second set I had my chances, I was so tight. But I went to the bathroom [after the second set] and I said to myself 'I want this'. Now I am in the final, I will enjoy, I have all the power with me."

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.

Lorenzo Musetti headlined a day of shocks at the Monte Carlo Masters as Felix Auger-Aliassime fell to a first-round defeat.

Auger-Aliassime already has one singles title to his name this year, having prevailed in Rotterdam, and also reached the final of the Open 13 in Marseille and helped Canada to victory in the ATP Cup at the start of 2022.

However, the sixth seed entered this contest with just one win from his last four matches and came unstuck once again at the hands of Musetti. 

Musetti, who won two sets in the fourth round of the French Open against Novak Djokovic last year, is very much at home on the clay in Monaco.

He demonstrated that in 6-2 7-6 (7-2) success, setting up a last-16 meeting with Diego Schwartzman.

“I live here and practice here,” Musetti said in his on-court interview. "It is nice to be here and play here in front of such a crowd. I am really happy.

"My backhand down the line was a key to many of my great shots. After a really good first set, he came back with such powerful serving, but I was calm and patient and that was the most beautiful thing about today."

Auger-Aliassime's exit came a day after top seed Djokovic was knocked out in the second round by Alejandro Davidovich Fokina, but there were no such problems for second seed Alexander Zverev as he saw off Federico Delbonis in straight sets.

Fifth seed Andrey Rublev came from a set down to defeat Alex de Minaur and fourth seed Casper Ruud, coming off his defeat in the final in Miami, edged qualifier Holger Rune in two tight sets.

The man who vanquished Ruud in Florida will go no further on the Cote d'Azur, however, Carlos Alcaraz losing in just over three hours to Sebastian Korda on his Monte Carlo debut.

Korda lost to Alcaraz in the final of last year's Next Gen ATP Finals, but avenged that defeat with a 7-6 (7-2) 6-7 (5-7) 6-3 victory.

World number 10 Cameron Norrie lost to Albert-Ramos Vinolas and his British compatriot Dan Evans fell to David Goffin, while 16th seed Lorenzo Sonego was beaten by the in-form Laslo Djere.

Elsewhere in the draw, there were wins for Jannik Sinner, Taylor Fritz, Hubert Hurkacz and Pablo Carreno Busta.

World number one Novak Djokovic explained that he could just not get up to the level of sharpness required in his shock defeat at the Monte Carlo Masters.

Djokovic slumped out in the second round on Tuesday when he lost 6-3 6-7 (5-7) 6-1 to world number 46 Alejandro Davidovich Fokina.

The Serbian's status as an unvaccinated player has limited his ability to compete on the ATP Tour this year and he has played in just one tournament so far, getting to the quarter-finals in Dubai. 

Yet his preparations for the French Open, which starts at the end of next month, hardly got off to a good start as he made 51 unforced errors in what was still, despite his rustiness, a surprise defeat.

"I didn't like the way I felt physically in the third. I just ran out of the gas completely," Djokovic told the media. 

"Just couldn't really stay in the rally with him. I mean, if you can't stay in the rally, not feeling your legs on the clay, it's mission impossible.

"I'm going to look with my team into reasons why that was the case and go back to the drawing board. Hopefully next week will be better in Belgrade."

Though Djokovic has won twice in Monte Carlo, it has not been a happy hunting ground for him in recent years. He has not advanced past the quarter-final stage since 2015.

He added: "It's going to take some time for me to really feel my best on the clay.

"That's historically always been the case. [I have] never played very well in the opening tournaments of the clay season.

"But it's okay. Obviously it is what it is. I have to accept the defeat and keep working."

While unhappy with his own performance, Djokovic had nothing but praise for his opponent. 

"I would like to congratulate Alejandro. He was the better player," Djokovic said. "He managed to find a better rhythm I think in the first two sets. I was hanging on the ropes the entire match. I was really chasing the result constantly.

"I always believed that I could come back and win the match, and I stayed there even though a lot of things were against me in terms of how I felt on the court. Game-wise, physically I was just far from my best.

"I expected this match to be [a] really tough match, [a] physical battle, and that's what it was. Unfortunately I'm on the shorter end of the stick, and my week ends here."

Djokovic's defeat also means a mouthwatering contest with teenager sensation Carlos Alcaraz, who he might have met in the quarter-finals, will not be taking place.

Novak Djokovic suffered a stunning defeat in his first ATP Tour match since February, the world number one losing in the second round of the Monte Carlo Masters to Alejandro Davidovich Fokina.

Djokovic's status as an unvaccinated player has limited his ability to compete on the tour this year. He missed the Australian Open in January after a saga surrounding his visa eventually resulted in his deportation on public health grounds, while laws around vaccination against COVID-19 in the United States prevented him from playing at Indian Wells and Miami.

Despite his inactivity, the Serbian - whose sole appearance on tour this year came during a run to the quarter-finals in Dubai - was expected to prevail on the clay against his Spanish opponent after receiving a bye in the first round.

But there were evident signs of rust in a mistake-riddled display against the world number 46, who remarkably emerged victorious to set up a meeting with either Dan Evans or David Goffin.

The tide looked to have turned in the second set tie-break, when an exquisite whipped forehand from Djokovic sent the match to a decider.

However, Djokovic, who committed 51 unforced errors, immediately surrendered the momentum by dropping serve in the first game of the third and he was broken twice more as Davidovich Fokina powered to a 6-3 6-7 (5-7) 6-1 victory in just under three hours.

"I knew that Nole hasn't had that confidence because he didn't play a lot," Davidovich Fokina said.

"This win is so special for me. I look at him every tournament. Here in Monte Carlo, full people [capacity], against the number one, I enjoy every moment."

Earlier, Evans saw off Benjamin Bonzi while Goffin, fresh off his triumph in Marrakech, came through against Jiri Lehecka to set up their second-round meeting.

Tenth seed Taylor Fritz defeated Monegasque wild card Lucas Catarina in three sets and 16th seed Lorenzo Sonego saw off Ilya Ivashka in straight sets. Laslo Djere, a semi-finalist in Marrakech, also progressed to the second round.

Carlos Alcaraz is hopeful of meeting Novak Djokovic in the Monte-Carlo Masters, but his first focus is on a second-round tie with Sebastian Korda. 

Alcaraz is one of the brightest prospects on the ATP Tour, with the 18-year-old Spaniard having won his first Masters title at the Miami Open and become the youngest men's champion of that tournament. 

That was Alcaraz's second title of 2022 and third overall. He is now up to 11th in the ATP world rankings. 

Seeded eighth, Alcaraz has been handed a bye to the second round but is in the same quarter of the draw as world number one Djokovic, who has triumphed twice in Monte Carlo. 

Alcaraz, though, is making sure not to get ahead of himself and think too much about a maiden meeting with Djokovic, with American Korda – who defeated Botic van de Zandschulp in his first-round match – first up. 

"I don't want to be in a rush, I just focus on the first [match]," Alcaraz told reporters ahead of what is a rematch of the Next Gen ATP Finals championship match which he won in straight sets. 

"Obviously, it would be a great match against Novak. 

"Playing against the number one player in the world [would be] amazing for me, but I hope to play well in the first [matches] and hope to meet him in the quarter-finals." 

Alcaraz seems set to have a future at the very top of the game but is insisting everything must be taken step by step. 

"Sometimes it is difficult, but I am trying to make it easy," he said. 

"Doing everything for the first time, I am trying my best, trying to manage the nerves of the first time well." 

Taylor Fritz, who won a Masters title at Indian Wells earlier this year, could also be standing in the way of Alcaraz and the quarter-finals, should the American defeat wildcard Lucas Catarina and Marin Cilic. 

Djokovic, on the other hand, faces Alejandro Davidovich Fokina in his first match. 

Stan Wawrinka's ATP Tour return at the Monte-Carlo Masters ended in defeat, while Jannik Sinner came through a tense encounter with Borna Coric. 

The former world number three made his comeback after more than a year out with a left foot injury that required two surgeries but fell to a 3-6 7-5 6-2 defeat to Alexander Bublik in the first round. 

Wawrinka, who entered the tournament as a wildcard having slipped to 236 in the world rankings, came from a break down to take the opening set but fatigue eventually set in and he was eliminated after two hours and seven minutes. 

"I think the body's getting much better," said Wawrinka, who lost in straight sets to Elias Ymer at a Challenger tournament in Marbella two weeks ago. 

"I'm still far away from where I want to be, but I think I'm [going in] the right direction. I think today was a positive match. It was a tough loss, of course, but I'm happy with the way I was playing today. 

"I was playing better, feeling better on the court physically. I spent a lot of mental energy to focus, to stay there as it was tough at the end. But I'm happy with what I have done."

Ninth seed Sinner was taken the distance by Coric before completing a 6-3 2-6 6-3 victory to advance to the second round. 

Sinner took a medical timeout in the second set while he dealt with some apparent abdominal pain, but he was able to battle back and take the win. 

Diego Schwartzman needed over three hours to come from behind and defeat Karen Khachanov 6-7 (5-7) 6-3 6-3, while his fellow Argentine Federico Delbonis set up a clash with second seed Alexander Zverev by besting Jaume Munar 6-4 3-6 6-4. 

Reigning champion Stefanos Tsitsipas faces a meeting with Fabio Fognini in the second round after the Italian overcame Arthur Rinderknech 7-5 4-6 6-3.  

There were also wins for Hubert Hurkacz, Pablo Carreno Busta, Marin Cilic, Alex de Minaur, Albert Ramos-Vinolas and Sebastian Korda. 

American Reilly Opelka defeated compatriot John Isner 6-3 7-6 (9-7) to win a history-making final of the US Men's Clay Court Championships in Houston.

In a clash between two of the tour's elite servers, and two of the tallest men to ever play professional tennis, break points were hard to come by, and even harder to convert, as Opelka saved all eight opportunities he faced, while Isner saved four out of five.

That one break decided the first set, as 6ft 10in Isner fought back from 40-0 down to force deuce, but the fourth break point of the game was converted by 6ft 11in rival Opelka.

The ATP said their respective heights made it the tallest tour final in the Open Era.

In a match that was always likely to be decided by whoever served best, Opelka had five aces to Isner's two in the first set, while Isner also had the only double fault.

Isner was much stronger in the second set, creating seven break-point opportunities, but he just could not win the important points as Opelka's serve repeatedly got him out of trouble.

Isner then had three opportunities at set point in the tie-break to force a decider, but it was Opelka's day, as he saved all three and converted his first chance at match point.

After dropping a set in his first-round match against Mitchell Krueger, Opelka was perfect the rest of the tournament, beating Gijs Brouwer and Nick Kyrgios in straight sets on his way to the final.

David Goffin secured his sixth ATP Tour title by coming from behind to beat Alex Molcan in the Grand Prix Hassan II final on Sunday.

Slovakian Molcan, in search of a first triumph at main tour level, came flying out of the blocks, but ultimately Belgian Goffin's experience showed as he recorded a 3-6 6-3 6-3 victory.

World number 65 Molcan, who defeated Goffin in the first week of the season in Melbourne, was in early control of this meeting in Marrakesh, a set to the good and serving at 2-1 up in the second.

However, former world number seven Goffin responded from that point onwards and did not look back as he won in one hour and 58 minutes.

Goffin feels he can take confidence from this success into the rest of the clay-court segment of the 2022 season.

"I'm very happy, proud of my week. It was not easy, a lot of tough matches," Goffin said. "But at the end, I have my sixth title, here in Marrakesh. It gives me a lot of happiness and confidence for the season on the clay.

"It was the case twice before that match that I lost the first set and I always stayed calm the whole week to turn it around. It was the case again today, because he was playing well.

"He was better than me in the first set, and then I managed to play better and better, serving better, being more aggressive in the middle of the second. I was the better player [after that]."

Quoted on the ATP website, Goffin said: "I was playing even better in the third set, so I'm really happy the way I finished with another break [and] a good match point. I didn't want to serve for the match, I preferred to finish with a break."

Molcan reflected on a positive week in Morocco that saw him most notably beat top seed Felix Auger-Aliassime.

"It was an amazing week for me," he said. "I won a lot of matches and enjoyed it very much."

Reilly Opelka and John Isner will meet in the US Men's Clay Court Championship final in Houston, after they claimed semi-final wins on Saturday.

Opelka kept up his strong early-season form with an imposing 6-3 7-5 victory over Nick Kyrgios in the first semi-final, getting the job done in just one hour and nine minutes.

Opelka slung down 18 aces to 11 from Kyrgios and faced only one break point across the contest.

The 24-year-old Opelka won a title in Dallas in February and followed up with a run to the Delray Beach final, with a third trophy match of the season now awaiting him.

The American world number 18 said he admired the "intangibles" from Kyrgios that "you can't teach."

"He's got one of the best serves in the world and when he turns it on he can come up with some shots that not many guys outside the top 10 can," Opelka said in his on-court interview.

Opelka enjoyed the high-tempo match with Kyrgios, who typically wastes no time between points.

"I prefer to play at that speed rather than, for example, Rafa [Nadal] where it's 50-55 seconds between points," Opelka said.

"It's a totally different speed here and I thought I did a good job managing the whole tempo of the match. I put a lot of returns into play and I came up big with my second serve."

He will face 2013 Houston champion Isner, who came from a set down to defeat defending champion Cristian Garin 4-6 6-3 6-4.

The 36-year-old's serve improved as the match went on and ultimately propelled him to victory, facing four break points in the opening set, one in the second and none in the decider.

Isner also served 17 aces on his way to the final, and won 80 per cent of points on his first serve.

"It's never easy when you have to come back from one set down," he said. "My serve certainly helped me out a lot. I didn't have to hit too many balls there in the end, and I didn't want to.

"I'm so happy to be in the final again here. At my age you never really know when you can get back to a final of a tournament like this."

David Goffin is wary he will face "a great fighter" when he tackles Alex Molcan in Sunday's final of the Grand Prix Hassan II in Marrakesh.

Experienced Belgian Goffin is a five-time tournament winner on the ATP Tour, and his Slovakian opponent is chasing his first title at this level.

However, their one past meeting went Molcan's way when they met in the Melbourne ATP 250 tournament in January, and although that match was on hardcourts and this final is on clay, Goffin respects his left-handed opponent's game.

Goffin made sure of his place in the title match with a 6-3 6-3 win over Argentinian Federico Coria, while Molcan, who beat Felix Auger-Aliassime earlier in the week, was a 6-1 7-5 victor against Serbian Laslo Djere.

Speaking of the threat posed by Molcan, Goffin said: "He's a great fighter, he's moving so well. He's lefty, so he's using his lefty game really well on clay, especially two days ago against Felix, he played well. So it's a tough opponent."

Goffin, quoted on the ATP Tour website, said he was pleased to get his clay season under way in fine style, even if he felt jittery at times against Coria.

"I managed to deal with my emotions at the end to finish the match, so I'm happy to play another final, especially here, the first tournament on clay," Goffin said. "I will give everything tomorrow."