Team Europe are poised to seal yet more Laver Cup glory after producing another dominant display against Team World, though the focus was on Nick Kyrgios following comments about his long-term future.

Europe swept Saturday's four matches in Boston to stand on the cusp of a fourth consecutive Laver Cup triumph – the defending champions lead 11-1 and require just two more points to clinch the title.

Stefanos Tsitsipas blitzed Team World's Kyrgios 6-3 6-4 at TD Garden, where Olympic Games gold medallist Alexander Zverev beat John Isner 7-6 (7-5) 6-7 (6-8) 10-5 before US Open champion Daniil Medvedev made light work of Denis Shapovalov 6-4 6-0.

Team Europe secured their fourth win of the day in the doubles – Tsitsipas and Andrey Rublev teaming up to defeat Isner and Kyrgios 6-7 (8-10) 6-3 10-4.

After Kyrgios' straight-sets loss to Greece's Tsitsipas, the 26-year-old Australian star casted doubt over his tennis future.

"This is my probably my last Laver Cup," former world number 13 Kyrgios – an Australian Open and Wimbledon quarter-finalist – told reporters post-match. "I don't know how much longer I will be in tennis.

"This is my last event of the year. I will get my body right ahead of the Australian Open.

"My mum is not doing too well with her health. I'd like to go back and see her."

"As long as I'm on the court, I will try and give my best, but I'm not going to lie and say that I'm going to plan to play four or five more years on tour," Kyrgios said. "That's just not me."

Playing for the first time since earning his maiden grand slam trophy at the expense of record-chasing Novak Djokovic at Flushing Meadows, world number two Medvedev suffered no letdown against Shapovalov.

"I played unbelievably, especially [in] the second set," Russia's Medvedev said in his on-court interview. "I didn't know what to expect because after the US Open, I didn't play for a week and a half. Came here, practised as much as I could the past three days, so I didn't hit [that] many balls, but was surprisingly feeling well.

"I wanted to show that also today. [The] first [set] was not easy, the ball was not going as fast as I wanted [and] he was playing really good. And then I just couldn't miss a ball anymore. I'm really happy about [that]."

Team Europe are on track for their fourth consecutive Laver Cup triumph after earning an early 3-1 lead against Team World.

Opening-day honours went to Bjorn Borg's Team Europe at TD Garden in Boston, where the defending champions moved into the box seat thanks to wins for Andrey Rublev, Matteo Berrettini and Casper Ruud in the singles on Friday.

John Isner and Denis Shapovalov managed to get Team World on the board in the evening's final doubles match against Alexander Zverev and Berrettini 4-6 7-6 (7-2) 10-1.

Roger Federer and Rod Laver were in the crowd as Team Europe – headlined by newly crowned US Open champion Daniil Medvedev and consisting of six of the world's top 10 – made a strong start courtesy of Norwegian Ruud, who overcame Reilly Opelka 6-3 7-6 (7-4), improving his career record to 3-0 against the towering American, and beating him in straight sets for the first time.

Italian star Berrettini then overcame Team World's Felix Auger-Aliassime 6-7 (3-7) 7-5 10-8 in the competition's longest match at two hours, 52 minutes.

Berrettini escaped with the second set after facing two break points in the penultimate game before prevailing against the Canadian in a thrilling match tie-break.

"One of the best matches bar none that I've ever seen played, absolutely just enthralling," said captain John McEnroe, whose Team World are eyeing their first Laver Cup trophy.

Rublev rallied past Argentina's Diego Schwartzman, who won the opening set and led 6-2 and 8-5 in the match tie-break before losing 4-6 6-3 11-9.

"Today we are a bit more lucky; Matteo won a tough match against Felix in a super tiebreak, now you saw my match," said Russian star Rublev.

"It was so close; Diego was leading all the super tiebreak, but in the end I find a way to win.

"This happens. This is tennis, this is sport. It’s emotions. Someone has to win, someone has to lose."

On day two, Stefanos Tsitsipas and Zverev headline the day session against Team World's Nick Kyrgios and Isner.

In the evening, Medvedev will meet Shapovalov before Rublev and Tsitsipas team up for a doubles battle with Kyrgios and Isner.

Novak Djokovic is well aware of the history he is poised to make in Sunday's US Open final, and he is not shying away from it. 

After his 4-6 6-2 6-4 4-6 6-2 defeat of Alexander Zverev in the semi-finals Friday, a win in the final against Daniil Medvedev would make Djokovic the first player since Rod Laver in 1969 to win all four majors in the same year.

It would also give him a record 21st grand slam title, breaking the mark he shares with Roger Federer and Rafael Nadal. 

Two astonishing achievements, neither of which is complete just yet, as Djokovic reminded observers by invoking a famous Kobe Bryant line. 

"Job is not done," Djokovic said. "Excitement is there. Motivation is there, without a doubt. Probably more than ever. But I have one more to go."

Djokovic did cross one statistical milestone off the list with Friday's win. He has now reached his 31st grand slam final, equalling Roger Federer's record. 

Since falling to Kei Nishikori in the last four at the 2014 US Open, Djokovic is 17-1 in grand slam semis. 

Zverev lauded Djokovic for his mental toughness as the world number one improved to 36-10 in five-set matches, but the top seed said he still has to fight himself to stay in control in high-pressure situations. 

"It's kind of a hurricane, a tornado, of emotions that you're going through in a sequence of one set or even one point," Djokovic said. "You are by yourself on the court, so there is no escape.

"You've got to find a way. And I think, over the years, I have managed to develop a formula that works for me. ...

"Tennis is a very beautiful sport but a very demanding sport and you've got to have mind and body balanced at all times if you want to compete at the highest level for the biggest trophies."

Few can match him on that stage and he will attempt to reach even greater heights with a win Sunday. 

His opponent, the second-seeded Medvedev, has dropped only one set on the way to the final. 

Djokovic beat him in straight sets in January to win the Australian Open and deny the 25-year-old Russian his first grand slam title. 

History will be on the line Sunday at Arthur Ashe Stadium, and Djokovic is embracing it. 

"There's only one match left. ... Let's do it,'' he said. "I'm going to put my heart and my soul and my body and my head into that one. I'm going to treat the next match like it is the last match of my career.''

To hear Alexander Zverev tell it, he would have needed to be perfect to beat Novak Djokovic in the US Open semi-finals. 

In the end, a wobbly beginning to the fifth set proved the German's undoing in a 4-6 6-2 6-4 4-6 6-2 defeat Friday simply because Djokovic was at his best when it mattered most. 

Combine that enduring quality with the Serbian's incredible statistical record, said Zverev, and you have the greatest player of all time.

Djokovic will have a chance to solidify that case Sunday when he faces Daniil Medvedev for the title. 

A victory would make the 34-year-old the first player since Rod Laver in 1969 to win all four majors in the same year and give him a record 21st grand slam title, breaking the mark he shares with Roger Federer and Rafael Nadal. 

"I think it's great for the sport," Zverev said after his loss. "Nobody thought anybody will do it again, what Rod Laver did. To see ]Djokovic] have the chance on Sunday, I do believe that he will do it is great. He's breaking every single record that there is.

"If you look at the stats, if you look the pure game of tennis action, he's the greatest of all time.

"Nobody is there with him, because most weeks world number one, most Masters 1000s titles, most likely going to be the most grand slams at the end of the day.

"And he has the chance of winning all four in the same year. How do you compete with that?"

Zverev certainly tried Friday, becoming the first player to push Djokovic to a fifth set since Stefanos Tsitsipas in the French Open final. 

"I fought back," he said. "I left it all out there. ... I mean, the match could have gone both ways, but it went his way. Very often it does."

On this night, Zverev said, it was largely Djokovic's serve on big points that boosted the top seed. 

Whatever shots happened to be working better than others for Djokovic, though, one factor stood above the rest, as it usually does for him at grand slams. 

"I think mentally he's the best player to ever play the game," Zverev said. "Mentally, in the most important moments, I would rather play against anybody else but him."

Novak Djokovic is one win away from becoming the first man to complete a Grand Slam in 52 years. 

The world number one fought back to defeat Alexander Zverev 4-6 6-2 6-4 4-6 6-2 Friday in the US Open semi-finals to put himself on the brink of history. 

Djokovic will face second seed Daniil Medvedev in Sunday's final as he attempts to win a record 21st grand slam title and become the first man since Rod Laver in 1969 to win all four majors in a calendar year. 

Laver was in attendance at Arthur Ashe Stadium to watch the top seed exert his will as he has done in so many five-setters over the years, breaking down the younger player over the course of the match to emerge with yet another triumph. 

Zverev had ended Djokovic's chances of a Golden Slam with a semi-final win at the Tokyo Olympics, rallying for a three-set win after dropping the opening set, but the script was different Friday. 

It started with Djokovic losing the opening set for the fourth successive match in New York. In the previous three rounds, he did not drop more than three games in any subsequent set, but Zverev made him work harder this time. 

With the first set even at 4-4, Djokovic fell behind 15-40 and double faulted on break point to give Zverev the opening he needed. Though his next service game was a bit shaky, Zverev managed to take the set when Djokovic mis-hit a forehand.

The German's momentum did not last, though, as he returned the favour by double faulting on break point in his first service game of the second set and watched Djokovic level the match with relative ease. 

Zverev had a chance to take control early in the third, earning two break points at 2-2, but he failed to convert and did not get another chance. When Djokovic had a similar opportunity up 5-4, though, he closed it out.

Down 0-40 in that game, Zverev saved two break points – the latter via an epic 53-shot rally that was the longest at this year's US Open – but Djokovic slammed home an overhead winner on the next point to take the set. 

Zverev shook off that disappointment and put the pressure back on Djokovic by hammering a forehand winner down the line to break the top seed and take a 2-1 lead in the fourth.

The German did not falter the rest of the set, eventually serving it out to force a decider and push Djokovic to a fifth set for the first time since the French Open final against Stefanos Tsitsipas. 

Djokovic jumped to an early lead in the fifth, forcing Zverev to the net on break point in the second game with a beautiful drop shot before finishing the younger player off with a cross-court winner. 

Djokovic reeled off four consecutive points to break Zverev in his next service game, then held at love to put the fourth seed on the brink at 5-0. 

Zverev, a winner in seven of his previous eight five-setters, did not surrender, breaking Djokovic thanks to a double fault on game point to pull within 5-2. 

But Djokovic ended it there, breaking back to close out the match in the next game as Zverev sent a forehand into the net from the baseline.

DATA SLAM

With the victory, Djokovic improved to 34-2 in night matches at Arthur Ashe Stadium and 36-10 in five-set matches in his career, winning his last seven in a row. 

WINNERS/UNFORCED ERRORS

Djokovic – 41/49
Zverev – 49/50

ACES/DOUBLE FAULTS

Djokovic – 12/2
Zverev – 16/8

BREAK POINTS WON

Djokovic – 5/8
Zverev – 3/12

Novak Djokovic knows he faces a tough challenge in his US Open semi-final with Alexander Zverev after coming from a set down to beat Matteo Berrettini.

The Serbian triumphed 5-7 6-2 6-2 6-3 to thwart Berrettini's revenge mission, having defeated the Italian in this year's Wimbledon final.

The world number one now faces the man who denied him a shot at the Golden Slam, with Zverev dumping Djokovic out of the semi-finals at Tokyo 2020.

And the 20-time grand slam winner was full of praise for his next opponent.

"He's in tremendous form, he's been winning a lot," said Djokovic, who still has the Calendar Grand Slam in his sights. "He has comfortably moved to the semi-finals here.

"I know his game well, we played in Tokyo. He's one of the best players in the world, but the bigger the challenge the more glory in overcoming it."

Reflecting on his victory over Berrettini, Djokovic felt he found his best form after dropping the opening set.

"This was a great match, with a lot of energy on and off the court," he said. 

"Matteo is a terrific player and every time we face each other it's a close battle.

"When I lost the first set, I managed to forget about it and move on. I was locked in at the start of the second and it was the best three sets I've played so far."

Alexander Zverev is riding a wave at the US Open after his confidence-boosting win over world number one Novak Djokovic en route to claiming gold at the Olympic Games.

Zverev survived a first-set scare to power past Lloyd Harris 7-6 (8-6) 6-3 6-4 in Wednesday's US Open quarter-final.

The German fourth seed will face either Djokovic, who is bidding to become just the third man to complete a calendar Grand Slam and first since 1969, or Matteo Berrettini for a spot in the men's final at Flushing Meadows.

Zverev – last year's US Open runner-up – said he has been fuelled by his semi-final win over Djokovic at the Tokyo Games.

"It's the biggest tournament in the world, Tokyo. It's the Olympics," Zverev said during his post-match news conference.

"Winning there against the world number one, especially that I was down a set and a break, being kind of out of the match, then coming back, it was different than the other matches. The emotions were different.

"Also securing a medal for Germany was very special to me. This year it seems like nobody can beat him in a big match, nobody can beat him at the grand slams.

"I feel like I was the first player to beat him in a very big match this year. That does give you something. To any person it would give you something.

"As I said before also, I think it was very important for me to back it up in the finals, back it up in Cincinnati. Hopefully I can continue this streak."

Zverev is in the midst of a career-best 16-match winning streak and has clinched 37 of 40 sets on the hard courts after winning Olympic gold and his fifth career ATP Masters 1000 crown in Cincinnati.

The 24-year-old is bidding to become the second man in history to win Olympic gold medal and the US Open/US Championships title in the same season, after Andy Murray in 2012.

On preparing against Djokovic, Zverev added: "You have to be perfect, otherwise you will not win.

"Most of the time you can't be perfect. That's why most of the time people lose to him. Against him, you have to win the match yourself. You have to be the one that is dominating the points. You have to do it with very little unforced errors.

"He is the best player in the world. He is very difficult to beat. But he's still also got to win tonight. He's playing Matteo Berrettini who is in very good form, finals of Wimbledon. I think he's looking forward to that match, as well. It's going to be an interesting match to watch those two."

Alexander Zverev won his 16th match in a row with a straight-sets victory over Lloyd Harris on Wednesday to reach the US Open semi-finals.

The fourth seed saved a set point from Harris in a tense opener and built on that to earn a 7-6 (8-6) 6-3 6-4 triumph in a little over two hours.

Zverev has dropped just one set across his five matches at Flushing Meadows this year and will face either Novak Djokovic or Matteo Berrettini as he seeks a place in back-to-back finals.

"I just hope their match goes on for eight hours and 30 minutes," Zverev joked when asked who he would prefer to face in the semi-finals.

"I didn't have a lot of chances on Harris' serve today and somehow managed to win that first set, which loosened me up a little bit and I started playing a lot better.

"In the third set, he started swinging. He started playing incredible tennis. So yeah, I'm happy to be through in three."

Harris beat three top-30 seeds to make it to this stage and more than held his own in the opening set against Zverev, who lost to Dominic Thiem in last year's final.

After sharing a break of serve apiece, Harris led 6-5 in the tie-break but lost the next three points to offer his opponent a platform to build from.

Despite struggling with a minor back problem, Zverev took advantage of his unseeded opponent's five unforced errors by holding throughout the second set.

The four-time grand slam semi-finalist raced into a 4-0 lead in the third set, but Harris slowly regained his composure and claimed the next three games.

Zverev's monster serve came to his rescue, however, as he took the eighth game and eased over the line in style with his 21st ace of the contest.

DATA SLAM

Zverev did not have things all his own way as he struggled in the opening set and was sloppy when leading 4-1 in the final set, but he ultimately proved too strong for an opponent ranked 46th in the world.

Last year's beaten finalist Zverev has served 83 aces and just 15 double faults across his first five matches and won 82 per cent of his first-serve points against Harris. Whether it is Djokovic or Berrettini, a tougher test awaits in the semi-finals.

WINNERS/UNFORCED ERRORS

Zverev – 43/26
Harris – 34/26

ACES/DOUBLE FAULTS

Zverev – 21/5
Harris – 13/1

BREAK POINTS WON

Zverev – 4/9
Harris – 2/3

Tokyo Olympic gold medalist Alexander Zverev refused to get carried away about his chances of winning his maiden major title despite easing into the US Open fourth round on Saturday.

The German fourth seed was leading 3-6 6-2 6-3 2-1 when Jack Sock withdrew with a groin issue which had been plaguing him throughout the match.

Zverev's walkover victory extended his winning run to 14 matches, dating back to his Tokyo 2020 gold medal triumph along with last month's Cincinnati Masters victory.

Reigning champion Dominic Thiem along with Rafael Nadal and Roger Federer all withdrew from the US Open prior to the tournament, opening the door for a first time winner.

"I’m on a 14-match winning streak now," Zverev said during his on-court interview. "I’m playing well. That’s all I want to say, I don’t want to say anything else.

"We all know that Novak is the big favourite, we all know that Daniil [Medvedev] is playing incredible tennis, we all know that there are a lot of other players out there that are playing incredible tennis.

"I think my fourth-round match against Jannik Sinner is going to be extremely entertaining because he’s a young guy that is very hungry and I feel like that’s going to be a high-level match."

Zverev also spoke about his drive to succeed at majors, having struggled earlier in his career.

The German was runner-up at last year's US Open and made the semi-finals at this year's French Open and last year's Australian Open.

Zverev's hopes for going deep at Flushing Meadows will be aided by the premature end to his match with Sock, having won in straight sets in the first two rounds over Sam Querrey and Albert Ramos Vinolas.

The Olympics gold medalist was full of praise for Sock, who has been plagued by injuries, after a dominant opening set.

"Jack I think played the best set of tennis I've ever seen him play," Zverev said. "I did one unforced error in the whole set and I lost it, 6-3, without having really any chances.

"If he would have kept it up I probably would not have won the match… Afterwards when he gets injured, it's a shame because otherwise it would have been an incredible match I think."

Alexander Zverev believes his comeback victory over Novak Djokovic at the Olympics has paved the way for his fine start at the US Open.

Zverev came from a set down to defeat world number one Djokovic 1-6 6-3 6-1 at the semi-final stage in Tokyo, with the German going on to claim gold by beating Karen Khachanov in straight sets.

The world number four carried the winning form to Cincinnati, triumphing at the Western and Southern Open, and has made a smooth start at Flushing Meadows, where he lost out to Dominic Thiem in last year's final.

Zverev did not offer up a single break point in a dominant first-round win over Sam Querrey, and lost only four games when cruising past Albert Ramos-Vinolas 6-1 6-0 6-3 on Thursday.

"The process started at the Olympics for me, and the match against Novak," Zverev told reporters.

"That kind of started it off, because I was down badly, and I managed to win with great tennis.

"It was very important for me to kind of back it up in Cincinnati, because a lot of the times players that for the first time in their career win something really big like a grand slam title or a gold medal, they do tend to go downhill a little bit.

"So it was important for me to go to Cincinnati, to a place where I have never won a match before this year, and have a great tournament."

Another motivation for Zverev is the cruel fashion in which he lost to Thiem last year, when he surrendered a two-set lead.

"I mean I was the first man in 785 years to lose a US Open from two sets to love up and being a break up in the third set, serving for it in the fifth set, being two points away multiple times, it was painful," Zverev said with a smile.

"I still remember it, I remember it every single time I walk on this board but I take it as motivation because I'm back here to hopefully play a great tournament and win a grand slam title, that's what I’m here to do."

Zverev has now tallied up 40 wins in 2021 and 13 on the bounce, though the 24-year-old - who could meet Djokovic in the semi-finals - knows he has to maintain his strong service game to keep his best tennis.

"My serve is kind of the key to my game. When it's working I'm playing great. When it's not, I'm losing matches like I did at Wimbledon," he said.

"It's no secret that my serve is probably the most important shot in my game, and I'm happy with how it's working. The matches are not going to get easier and I will need that to be my weapon.

"I think it was always a problem of mine at the beginning of my career that I always spent a lot of hours, a lot of time in the beginning of grand slam tournaments. So it's nice to have two matches, winning [them] in straight sets."

Stefanos Tsitsipas has defended his "personal need" for long bathroom breaks after being jeered during his four-set second round win over Adrian Mannarino at the US Open on Wednesday.

The world number three triumphed 6-3 6-4 6-7 (4-7) 6-0 but was booed by the Arthur Ashe Stadium crowd after taking a bathroom break which exceeded seven minutes.

The Greek was criticized by Andy Murray, who said he lost respect for Tsitsipas after taking a lengthy break ahead of the final set in their five-set first round epic on Monday.

Alexander Zverev weighed in on the discussion, claiming Tsitsipas was communicating with his coach during his bathroom breaks, labelling them "ridiculous" and saying he had broken an "unwritten law".

Tsitsipas reverted to the rule book in his defence after beating Mannarino, insisting he had done nothing illegal and longer breaks were part of his "personal needs".

"It's just my personal needs," Tsitsipas told reporters. "Some people have other needs. Some people take much more than 25 seconds between points, which is fair.  

"I've done everything the right way. If I haven't I should be penalized. I completely agree with it. I should get a fine or be penalized if I haven’t followed whatever I've done correctly. But as far as I know, it is a necessity, it is a need when I'm out there playing and performing."

Tsitsipas said he felt fans who booed and jeered did not understand the game or his need to take longer bathroom breaks.

"I haven’t done anything wrong so I don't understand," he said. "The people love the sport, they come to watch tennis. I have nothing against them. But some people don't understand. They haven't played tennis at high level to understand how much effort and how much difficult it is to do what we are doing."

He added: "It is important. First of all, you carry less weight on you with all the sweat. You feel rejuvenated, you feel fresh, and you don't have all the sweat bothering you and coming in your face, on your fingers, everywhere all over your body. It makes you feel better.

"For me it is important to take that break. For someone else probably not. And everyone has his own time. I try and be as quick as I can. Sometimes I just need a bit more time."

Tsitsipas added that he was taken aback by the public criticism from Murray and Zverev.

"I never complain of what other players do," the 23-year-old French Open runner-up said. "My parents have taught me not to watch other people's business and concentrate on myself. Do my job.

"I just don’t understand when some players go and criticize other players, or during a match they put too much emphasis on it."

There have been calls for a hard cap on the permitted time for bathroom breaks, which American Sloane Stephens agreed with, speaking after her straight-sets win over 21st seed Coco Cauff.

"I don't think you should be gone from the court for six-eight minutes," Stephens said. "It's a long time to leave a match. That changes the whole momentum of a match.

"I can't speak for what happened in that match, but I do know on the girls' side, there still is a lot of that. It's gamesmanship.

"I think there definitely needs to be a rule or changes. They make a lot of rule changes for smaller things, like they took one minute off the warmup. If someone goes to the bathroom for nine minutes, no one says anything."

Alexander Zverev has accused Stefanos Tsitsipas of behaving like a junior and disrespecting his opponents by taking such long bathroom breaks during matches.

Andy Murray was furious when Tsitsipas was off court for around eight minutes ahead of the final set in their thrilling first-round match at the US Open on Monday.

Tsitsipas also required a medical timeout for a foot problem during a pulsating contest that the world number three won 2-6 7-6 (9-7) 3-6 6-3 6-4 at Flushing Meadows.

Murray said he had lost respect for the 23-year-old, who defended his lengthy spell off court and stated he had played by the rules.

The Brit was in no mood to back down on Tuesday, however, as he tweeted: "Fact of the day. It takes Stefanos Tsitsipas twice as long to go the bathroom as it takes Jeff Bezos to fly into space. Interesting."

Zverev appeared to accuse Tsitsipas of communicating with his father and coach, Apostolos, when he took a break during their semi-final showdown at the Western and Southern Open in Cincinnati this month.

Tsitsipas responded by denying having ever used his phone during such a situation, describing the accusation as "absolutely ridiculous."

However, world number four Zverev had Tsitsipas in his sights once again after beating Sam Querrey 6-4 7-5 6-2 in New York.

The German said: "It's happening every match. It's not normal. It happened to me in the French Open, to Novak at the finals [of the] French Open. I think Hamburg against [Filip] Krajinovic he was complaining, against me in Cincinnati was ridiculous, and now here again. I think players are catching up with that.

"He's the number three player in the world. I do not believe he needs to do that, because if you're top three in the world, you're one of the best in the sport.

"These kind of things happen at junior events, at Futures, at Challengers maybe, but not when you're top three in the world.

"You're allowed to do that but it's like an unwritten rule with players. I have been breaking rackets, I go insane sometimes and all that but one thing I'm very proud of, and I'll keep for the rest of my career, is I win and I lose by playing tennis on the tennis court."

Zverev reiterated his grievance with Tsitsipas having taken such a lengthy break during their meeting in Cincinnati.

"I didn't ask that question in Cincinnati, which I was very surprised at, because I was going to answer that very truthfully and honestly," he said.

"He's gone for 10-plus minutes. His dad is texting on the phone. He comes out and all of a sudden his tactic completely changed. It's just not me but everybody saw it. The whole game plan changes.

"I'm like, either it's a very magical place he goes to or there is communication there. But I also don't want to disrespect him. He is a great player, he is number three in the world for a reason. He's winning tournaments and playing incredible tennis this year for a reason, so it's not only that.

"But I do believe, and Andy said it as well, there is some level of respect that everybody needs to have between players.

"I feel like sometimes - or he might just go to the toilet. We don't know that, that's also possible. But it just happens too often, I would say."

Alexander Zverev believes world number one Novak Djokovic remains the favourite for the upcoming U.S. Open despite the German backing up his Olympic gold medal with victory in Cincinnati.

The German world number four defeated Andrey Rublev in straight sets on Sunday to win the Western and Southern Open, claiming his fourth title of the ATP season.

The 2021 U.S. Open begins next Monday with Dominic Thiem, who defeated Zverev in the 2020 final, withdrawing from the men's draw along with superstar Roger Federer and Rafael Nadal.

Their absences have opened up an opportunity for the in-form Zverev to have a run at the title but the German insisted Djokovic, who he defeated in the Olympic semi-finals, is the player to beat.

"I do think that he's still the favourite," Zverev told reporters after his win in Cincinnati.

"I do think he's going to be playing incredible tennis there. He's going to be fresh, and I think there is also other guys that are in very good form. I think Rublev is in very good form, [Daniil] Medvedev, [Stefanos] Tsitsipas, all those guys are playing great tennis.

"It's definitely going to be an interesting US Open. But I'm also looking forward to it, because I know where I stand, I know how I'm playing, and I hope I can continue the work and hopefully play even better in New York."

Djokovic has not played since Tokyo 2020, where he lost his bronze medal match to Pablo Carreno Busta after his semi-final defeat to Zverev.

The Serbian world number one opted to withdraw from the mixed doubles' semi-final afterwards, citing a left shoulder injury.

"I think Novak will be back. He's obviously going to be the favourite but I think other guys are going to be in great shape,” Zverev said.

"I'm looking forward to the week. Let's see how it goes. But there is still one week to go. I still have a lot of work ahead of me. I have to find my rhythm in New York, as well."

Zverev, who had never won a match in Cincinnati prior to this year's event, has not lost a match since his Wimbledon fourth-round exit to Felix Auger-Aliassime in July.

Alexander Zverev claimed his fourth title of 2021 with a 6-2 6-3 victory over Andrey Rublev to win the Western and Southern Open.

The Olympic champion had not won a match in Cincinnati prior to this year's tournament, but Sunday's one-sided final capped a remarkable turnaround for the world number five.

Zverev raced into a 4-0 lead before securing the opening set 6-2 as he produced no errors across the first seven games.

The third seed carried on his domination, breaking Rublev in his opening service game of the second set to pave the way for the 17th ATP title of his career within an hour in the showpiece.

After paying tribute to "his best friend on Tour" Rublev, Zverev added in his on-court interview: "It is incredible that tennis can be back, sport can be back, and we can watch and play this beautiful sport again.

"I normally do not look forward to this week - not winning a single match in seven years - but this has now become one of my favourite times of the year for me, hopefully it can be for the next 10 to 15 years."

The 24-year-old reached the final of the US Open last year, though he will now eye going one step further as the tournament commences at the end of August.