Nick Kyrgios

World number one Djokovic was stunningly disqualified after hitting the official with a ball during his last-16 clash with Pablo Carreno Busta.

It was not intentional, but nonetheless the Serbian's careless act saw him kicked out of the tournament he was favourite to win.

There is no love lost between Kyrgios, who has endured his own disciplinary issues, and Djokovic, with the Australian claiming he would suffer a far worse punishment.

He tweeted: "Swap me for jokers incident. 'Accidentally hitting the ball kid in the throat' how many years would I be banned for?"

Underneath was a list of three answers, offering followers to choose the length of his hypothetical ban in years.

Of the available options – five, 10 and 20 years – the latter was the most popular, with more than half of the almost 160,000 votes cast.

Kyrgios has been critical of Djokovic's approach to the coronavirus crisis, with the 17-time grand slam winner having organised an exhibition tour at which several players contracted COVID-19.

In May last year, Kyrgios was himself defaulted from a match after reacting badly to receiving a game penalty for unsportsmanlike conduct in a second-round clash with Casper Ruud at the Italian Open.

Kyrgios kicked out in disgust and launched a chair before walking off as he was disqualified by the umpire.

Djokovic did not partake in any media activities after his moment of madness, but he did post a message on Instagram.

"This whole situation has left me really sad and empty," he said.

"I checked on the line person and the tournament told me that thank God she is feeling ok. I'm extremely sorry to have caused her such stress. So unintended. So wrong. I'm not disclosing her name to respect her privacy.

"As for the disqualification, I need to go back within and work on my disappointment and turn this all into a lesson for my growth and evolution as a player and human being.

"I apologise to the @usopen tournament and everyone associated for my behaviour. I'm very grateful to my team and family for being my rock support, and my fans for always being there with me. Thank you and I'm so sorry."

Djokovic's exit means there will be a first-time major winner in the men's draw in New York.

Kyrgios came close to clinching his first grand slam title when he met Novak Djokovic in the Wimbledon final in July, taking the opener but ultimately succumbing to defeat in four sets on Centre Court.

The enigmatic Australian, who has never gone beyond the third round of the US Open, will begin his final major campaign of the year against his compatriot and doubles partner Kokkinakis on Monday.

But the 27-year-old is not enamoured by the prospect of a deep run in New York, revealing he struggles with being away from his homeland while playing on the ATP Tour.

"A big part of me just wants the US Open to be over so I can go home," he said on Sunday.

"It's brutal not being able to have the normality of your own bed or your own family for so long and then you have to deal with all this.

"The media, the fans, the training, the matches, the pressure, especially on my spectrum as well – it's not normal. So it's hard. It's really hard.

"I'm definitely feeling very exhausted. Just after Wimbledon, I didn't even have time to enjoy it.

"Everyone gets to go home on the tour. They get to take a cheeky little flight back home to reset. There's just no other type of tennis player who really understands that [homesickness] apart from the Australians.

"Whether I win or lose, it's going to be the same for me. It's a win-win for me. If I win, it's more money and another great result. If I lose, I get to go home."

Asked what he had gained from his thrilling Wimbledon run, Kyrgios said: "The confidence in myself to be able to do it over two weeks. Staying in a single spot for two to three weeks can be exhausting. 

"To know that I can do that and go about things the right way and take every practice session, every recovery session, the right way, it's confidence in the back of my mind. 

"But also, I'm the type of player that if I had won Wimbledon, I probably wouldn't have played the US Open."

Meanwhile, the US Open is set to mark a final grand slam appearance for legendary 23-time major singles champion Serena Williams, and Kyrgios believes she deserves to be considered the greatest player in the sport's history.

"Obviously it's a very special moment for her. She's probably the greatest of all time," he added.

"Whether or not we see anyone live the career that she has? I don't think that's possible."

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The Wimbledon runner-up began his latest quest for a maiden singles grand slam crown with a routine 6-4 6-4 7-6 (7-4) victory at Arthur Ashe Stadium on Monday.

It marked the first time the pair, who won the doubles event on home soil at the Australian Open in January, have met in a tour-level match.

Kyrgios will also partner Kokkinakis in the US Open doubles, and the 27-year-old did not enjoy facing his compatriot in singles competition.

"When we both saw the draw, it was a nightmare, honestly," Kyrgios said. "We never want to play each other. 

"I've just got so much respect for him. I can't wait to get out there and play doubles with him on the right side of the net.

"We just know each other's games like the back of our hand. We've played together since we were about nine years old. 

"He knows my game well. I know his game extremely well. I just played the bigger points well early on. We're going to play each other, hopefully, never again."

Kyrgios will now take on Benjamin Bonzi, who beat fellow Frenchman Ugo Humbert in five sets to advance at Flushing Meadows.

While Medvedev had the clear power advantage – finishing with 10 more winners and 11 more aces – he also allowed Wu to beat himself, with 18 unforced errors and three winners in the opening set.

Despite his early wastefulness, Wu still created six break point opportunities in the opening set, but could only capitalise on one. It would be his last break of the match as Medvedev tightened the screws down the stretch.

The Russian took the first four matches of the second set to take away any hope Wu had of fighting back into the contest, and in the third set Medvedev's serve really hit top gear.

He faced no break point opportunities in the final frame as he converted over 70 per cent of his points on both first serves (13-of-18) and second serves (eight-of-11), while Wu's errors returned, with 15 and just four winners.

Against Kyrgios next, Medvedev will be looking for his second win against the Australian in their fifth meeting. In their two matches this year – and their only two since 2019 – Medvedev won in four sets at the Australian Open, before Kyrgios got one back at the Canadian Open.

ACES/DOUBLE FAULTS

Medvedev – 12/5

Wu – 1/0

WINNERS/UNFORCED ERRORS

Medvedev – 26/27

Wu – 16/42

BREAK POINTS WON

Medvedev – 6/12

Wu – 1/8

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

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

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

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

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

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

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

Data Slam: Khachanov cool under pressure

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

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

ACES/DOUBLE FAULTS

Kyrgios – 31/5
Khachanov – 30/3

WINNERS/UNFORCED ERRORS

Kyrgios – 75/58
Khachanov – 62/31

BREAK POINTS WON

Kyrgios – 2/9
Khachanov – 4/8

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

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

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

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

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

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

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

Data Slam: Khachanov cool under pressure

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

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

ACES/DOUBLE FAULTS

Kyrgios – 31/5
Khachanov – 30/3

WINNERS/UNFORCED ERRORS

Kyrgios – 75/58
Khachanov – 62/31

BREAK POINTS WON

Kyrgios – 2/9
Khachanov – 4/8

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

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

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

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

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

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

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

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

Data Slam: Kyrgios accomplishes feat not seen since 1987

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

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

ACES/DOUBLE FAULTS

Kyrgios – 21/7

Medvedev – 22/2

WINNERS/UNFORCED ERRORS

Kyrgios – 53/38

Medvedev – 49/19

BREAK POINTS WON

Kyrgios – 5/7

Medvedev – 3/8

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The 2022 Wimbledon finalist made the claim to the chair umpire late in the second set of his hard-fought 7-6 (7-3) 6-4 4-6 6-4 win over the Frenchman at Louis Armstrong Stadium.

The chair umpire remarked that the smell could be coming from the kitchen which Kyrgios retorted with "it was f***ing marijuana".

"People don't know I'm a heavy asthmatic," Kyrgios told reporters after the match.

"When I'm running side to side, I'm struggling to breathe, probably not something I want to be breathing in in between points.

"Yeah, US Open, it's a very different vibe to everywhere else. I feel like Wimbledon was so proper. Australian Open, you kind of expect it there, being an Aussie.

"But here, it's just like noisy. Point in, point out, I can't barely hear. Half the time I can't even hear my team because it's so noisy all the time."

The latter half of Kyrgios' second-round match coincided with major drawcard Serena Williams playing on Arthur Ashe Stadium against second seed Anett Kontaveit.

"Ashe was unbelievably noisy," Kyrgios added. "I couldn't hear anything. Constant jitter. Things going off, sirens.

"In Armstrong today, hearing trains and people. For someone that's struggled to focus in my career, I'm really trying hard to put my head down and play point by point, try to dig myself out of some certain situations.

"It's hard because there's a lot of distractions. Obviously a lot of heckling going on as well. People are saying things. I got to be very careful with what I say these days."

Kyrgios' win means he will take on American J.J. Wolf in the third round on Friday and the 23rd-seed Australian, who won August's Citi Open in Washington DC, said he was feeling motivated and more professional than ever.

"This year's been amazing in so many different ways," he said. "For my tennis, I kind of wanted to almost reinvent myself, get back to the top of the game where I know I belong.

"The Wimbledon final was a turning point I think for me mentally. If I won that match, I don't know where my motivation would have been at. Losing it and being so close, it was really tough for me to kind of swallow that.

"Winning Washington, winning so many matches, I just feel like I thought the pressure would be off me after winning Wimbledon. He's a Wimbledon finalist, he's nearly-over-the-hump-type thing.

"I didn't think I'd be putting this amount of pressure on myself. Every day I come in, I watch what I eat, I try and get sleep. Like every practice session I try and have good intent. I almost don't know who I am anymore, to be honest, because that's not me.

"I feel like I'm really professional right now. I never thought that the Wimbledon final would make me that way. I thought it would be the other way, the reverse, almost a bit lax and a bit chilled with it."

Williams went down 7-5 6-7 (4-7) 6-1 to Ajla Tomljanovic – Kyrgios' former partner – on Friday in the third round of the US Open.

That brought an end to her playing career, though the 40-year-old suggested she would leave the door open for a potential return.

Kyrgios, who defeated J.J. Wolf to set up a contest with reigning men's champion Daniil Medvedev, is in awe of what Williams has achieved, as he ranked the 23-time grand slam champion alongside Rafael Nadal, Roger Federer and Novak Djokovic.

"She's had a career that I don’t think no one else will emulate," Kyrgios said.

"You've got a couple on the men’s side who are trying to catch her in grand slams, but Nadal, Serena, Federer, Novak, these are once in a generation athletes – I wouldn't even put myself in the same category, ever.

"It's a special moment for her, she played extremely well, she won two matches and nearly got on top [against Tomljanovic], it's a hell of a way to go out.

"I just appreciate what she's done and I'm sure everyone in this building does as well."

After beating Wu Yibing, world number one Medvedev said of Williams: "That was a crazy match, it was close to being three hours.

"It's definitely a pity that she lost. If it's the last match of her career, it was definitely an amazing match and she was really close to winning.

"Ajla played at a great level, it was not easy against the crowd and it was a high-level match."

Williams bows out with the most grand slam wins in the Open Era of any player, male or female.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The world number one will continue his men's single title defence against the Australian in the last 16 at Flushing Meadows after a 6-4 6-2 6-2 Win over China's Wu Yibing.

The pair are set to meet for the fifth time on the ATP Tour, with Kyrgios holding an impressive 3-1 record over the Russian in their previous four encounters, including in the final of the 2019 Citi Open.

But Medvedev defeated the former on home turf at the Australian Open earlier this year, in arguably the biggest clash between the duo.

Speaking ahead of the pair's encounter, Medvedev stressed he does not see the pair as friends, but he has strong admiration for his opponent's game and is impressed at how he has revived his fortunes this year.

"I don't think we are friends," he added. "I feel like we respect each other a lot. We are both quite electric. You never know what's going to happen in the future

"Nick is a little bit different from other tennis players on the court. That's his choice. That's his life. I'm not the one to judge. I feel a lot of respect for him."

Asked if he is surprised at Kyrgios' improved form following a first grand slam final this year at Wimbledon, Medvedev added: "To be honest, yes.

"We all knew that he's capable of doing big things. We always knew on [his] day, he is capable of beating anyone.He [has] proved it many times, against the biggest players in the world."

Kyrgios, meanwhile, is relishing another battle on a big occasion, adding that his attempts to seize victory against the odds of public opinion allow him to "thrive".

"You want to be in those moments," he said. "I want to be playing on the biggest stadiums in the world in front of millions of people broadcasted globally. That's where I want to be. That is why I work hard.

"It makes it even sweeter. I know a lot of people don't want me to succeed. I know a lot of people hate my game, the way I do things, the way I go about it. I always thrive on it. I never want to forget all the things people say.

"I always carry this chip on my shoulder. Win or lose, I'm proud of how far I've come. I think that's where every tennis player wants to be, playing the best players in the world in the best stadiums in the world."

Kyrgios dominated the match with his serve, racking up 21 aces to Wolf's five, and of the seven break point opportunities the Australian allowed, he saved all seven.

His return game was sharp as well, creating 11 break points and converting five, and he used it to break away in the second set, rattling off five consecutive games to comfortably go up two sets to love.

The third set was more competitive as Kyrgios had a pair of double faults, and more unforced errors (17) than winners (16), but he ultimately had too much firepower for the 23-year-old American.

After coming back from a love-40 deficit, saving four break points in the game, Kyrgios put the finishing touches on the straight sets win with another break of serve to seal it.

With the win, he books his spot in the fourth round, where he will meet world number one Daniil Medvedev.

Kyrgios has won three of the four career meetings between the pair, including their most recent fixture at the Canadian Open.

ACES/DOUBLE FAULTS

Kyrgios – 21/5

Wolf – 6/1

WINNERS/UNFORCED ERRORS

Kyrgios – 36/32

Wolf – 20/26

BREAK POINTS WON

Kyrgios – 5/11

Wolf – 0/7

According to Kyrgios' compatriot Cash, the Australian has taken the sport "to the lowest level" with his on-court behaviour in the first week of the tournament.

The 27-year-old beat fourth seed Stefanos Tsitsipas 6-7 (2-7) 6-4 6-3 7-6 (9-7) in an enthralling round-three tie on Saturday.

Tsitsipas accused his opponent of "constant bullying" after the ill-tempered clash, which was followed by a riposte as Kyrgios said the beaten Greek was "soft" and denied being a bully.

Kyrgios frustrated Tsitsipas by calling for him to be defaulted after the world number five narrowly missed a spectator when firing a ball into the crowd at the end of the second set.

The umpire was then labelled a "disgrace" during an extraordinary Kyrgios outburst, and his behaviour seemed to get under the skin of Tsitsipas, who was deducted a point for sending another ball towards the spectators before appearing to hit a couple of shots directly at his opponent's body.

Kyrgios has been a repeated critic of umpires and line judges, often appearing to show contempt to authority figures, and Cash – Wimbledon champion in 1987 – has had enough, calling out his countryman's conduct.

Speaking on BBC Radio 5 Live, Cash said: "It was absolute mayhem. He's brought tennis to the lowest level I can see, as far as gamesmanship, cheating, manipulation, abuse, aggressive behaviour to umpires, to linesmen.

"He was lucky to even get through the first set, he should have been defaulted in about the first set. Something's got to be done about it. It's an absolute circus.

"Is it entertaining? Yeah, possibly. But it's gone to its absolute limit now."

Asked how he considered Kyrgios to be cheating, Cash said: "The gamesmanship, the stuff that he was doing. The abuse that he was giving Tsitsipas.

"Tsitsipas would make a line call and he'd go up there and he'd start complaining, he was in his face. That's a part of gamesmanship. That's the sort of stuff that he does and I think there's a limit."

Cash's criticism comes ahead of Kyrgios facing American Brandon Nakashima on Monday. That match has been given the prize billing of first up on Centre Court, despite neither man being seeded.

The tennis authorities may not approve of some of the behaviour, but they know there is a huge public fascination with the highly talented Kyrgios, which is why that match has such a prestigious slot. He is 40th in the ATP rankings, and 20-year-old Nakashima is 56th on the list.

Kyrgios is just one win away from matching his best run at Wimbledon, having reached the quarter-finals in 2014 with a win over Rafael Nadal before being beaten by Milos Raonic.

Yet Cash indicated the loudmouthed showman should face sanctions for his actions.

"I have no problem with a bit of gamesmanship, but when it gets to that level I think it's out of control, and it was," Cash said.

"The umpire had lost control, the ball kids were running across the court as Kyrgios was serving. He didn't slow down for any of that stuff.

"Tsitsipas got sucked right in, so it was entertaining, and it was fascinating, but for me it's gone too far now."

Nadal, 36, has been vocal about his struggles physically during the tournament, but had been determined to push through the pain in an effort to keep his chances at the calendar slam alive, having already won this year's Australian Open and French Open.

During his quarter-final win against Fritz, family members were imploring Nadal to retire from the match as his clear discomfort appeared to be getting the better of him at times.

He admitted in his post-match media appearance that his condition worsened during the match, saying he will prioritise his health if he has to make a tough decision.

"I don't know [if I will be able to play] – I am going to have some more tests, but it is difficult to know," he said.

"I had these feelings for a couple of days, but without a doubt, today was the worst day. There has been an important increase of pain and limitation.

"I am worried. I don't have a decision. I need to know different opinions and I need to check everything the proper way.

"There is something more important than winning Wimbledon, and that is health."

The winner between Nadal and Kyrgios will face the winner of Novak Djokovic's semi-final against Cameron Norrie in the decider.

Two days on from an ill-tempered victory over Stefanos Tsitsipas that resulted in both players been fined, Kyrgios defeated 20-year-old Brandon Nakashima to progress to the quarter-finals of a grand slam for the third time in his career.

It will be the Australian's first appearance in the last eight of the singles draw at a major since 2015 in Melbourne, however, with his other grand slam quarter-final showing having come at Wimbledon in 2014 – Kyrgios having beaten Rafael Nadal to reach that stage on that occasion.

Cristian Garin of Chile is next up, after what was a reasonably well-mannered display against Nakashima, who Kyrgios was full of praise for.

Yet he still managed to spark some contention on Monday, having wore a red cap and a pair of red Nike Jordan trainers during his post-match on-court interview, breaching Wimbledon's strict dress code.

This was put to Kyrgios in his post-match news conference, with the journalist in question asking the 27-year-old if he thought he was above the rules.

"Because I do what I want," Kyrgios replied. "I'm not above the rules. I just like wearing my Jordans. I'll wear some [Jordan] triple whites tomorrow.

"Nobody else, even after Wimbledon, really walks with Jordans on the court. I don't moan [about controversy], I love it – more attention for me.

"What's that saying? Any publicity is good publicity, right?"

Kyrgios' fellow Australian Pat Cash said over the weekend that his compatriot had taken tennis to "the lowest level".

Yet Kyrgios insists he now laughs off criticism, which he believes is a sign of how he has matured as a player.

"Honestly, I don't care. I just smile. It's so funny. It's hilarious," he chuckled. "I almost just wake up and read things and just laugh.

"I never forget things people might have said three, four years ago, they stick with me. I have a massive chip on my shoulder.

"And I sit here now, quarter-finals of Wimbledon again, and I just know there's so many people that are so upset. It's a good feeling.

"I don't think in the past when I’ve got this far in a grand slam, or played big matches, I used to be on my phone a lot, attached to technology, seeing everyone's opinions or highlights, but I feel like I'm able to switch off from that, and that's a big part of my growth. Being obsessed with my girlfriend helps!

"I'm really able to just let that go, separate tennis and life, I think that's the most important thing."

Kyrgios produced an outstanding display to rally after losing the first set on No. 1 Court, eventually prevailing 6-7 (2-7) 6-4 6-3 7-6 (9-7) in an incident-filled match.

The enigmatic star set the tone with an incredible outburst after a frustrated Tsitsipas struck a ball into the crowd at the end of the second set, narrowly missing a spectator.

The Australian immediately called for his opponent to be defaulted, recalling Novak Djokovic's contentious exit from the 2020 US Open after he had accidentally hit a line judge in frustration after dropping a game.

Kyrgios could be heard calling the umpire a "disgrace", and then, after Tsitsipas had been let off with a warning, the unseeded talent asked: "Are you dumb?"

He then hit out at the umpire, yelling: "What are you talking about? Novak hit someone, it is the same, it happened right there. 

"Bring out more supervisors, I'm not done. You can bring them all out, I don't care. I'm not playing until we get to the bottom of it. 

"What happened to Novak when he hit the ball into a girl? She was injured. You can't hit a ball into the crowd and hit someone and not get defaulted."

But the drama was far from done as Tsitsipas flew into a rage of his own early in the third, having been hit with a point deduction for wildly firing another ball towards the crowd – but hitting the scoreboard instead – after Kyrgios produced a mischievous underarm serve when holding to love.

The fourth seed's frustration was evident as he then appeared to hit a couple of shots right at Kyrgios to boos from spectators, who vociferously cheered every point for the Australian.

But after producing some outstanding tennis to end the aggravated Tsitsipas' hopes of winning a first grand slam title, Kyrgios said he had no problems with the Greek, whom he played doubles with at Wimbledon in 2019.

"Honestly, it was a hell of an atmosphere, an amazing match, I honestly felt like the favourite coming in; I played him a couple of weeks ago, but I knew it was going to be a tough match," he said.

"He's a hell of a player, I had my own tactics out there – he knows how to play me, he's beaten me once, and obviously I've had success, so it was a hell of a match.

"I'm just super happy to be through, he was getting frustrated at times and it's a frustrating sport, that's for sure. I know you all think you can play, but it's very frustrating, whatever happens on the court, I love him."

Kyrgios now holds a 4-1 head-to-head lead over Tsitsipas, having also got the better of the world number five on the grass at the Halle Open earlier this month.

The 27-year-old also previously courted controversy during his run to the fourth round when he spat in the direction of a "disrespectful" fan during his first-round win over Paul Jubb.

But Kyrgios claimed his antics serve to drive interest in the sport, adding: "It's amazing, everywhere I go I seem to have full stadiums.

"The media loves to write that I'm bad for the sport, but clearly not."

Kyrgios produced an impressive display on No. 1 Court to down his Chilean opponent 6-4 6-3 7-6 (7-5), becoming the first unseeded Wimbledon semi-finalist since Rainer Schuttler and Marat Safin in 2008.

The Australian, who had lost two previous grand slam quarter-finals (at Wimbledon in 2014 and the Australian Open the following year) has courted controversy during a box-office run at SW19, spitting in the direction of a spectator during his opener last week before labelling Stefanos Tsitsipas "soft" after an ill-tempered third-round match.

And the 27-year-old, who took a moment to sit and savour his win before conducting his court-side interview, thought he had squandered any chance of grand slam success earlier in his career.

"Amazing atmosphere out here again, I just never thought I'd be at a semi-final of a grand slam, honestly, I thought my ship had sailed," he said.

"You know, I didn't go about things great earlier in my career, and may have wasted that little window.

"But I'm just really proud of the way I've come back out here, and of my team."

Kyrgios put the rows and trick-shots to one side during a professional performance, serving 17 aces and saving eight of the nine break points conjured by Garin.

Asked how he had found consistency without working with a full-time coach, Kyrgios said: "I don't have a coach, I would never put that burden on someone!

"Each and every one of my team plays a very important role, [but] I feel like no-one knows my tennis like I do. 

"I've been playing this sport since I was seven, and to reach a semi-final of a grand slam… I'm pretty happy."

Kyrgios' clash with Garin represented Wimbledon's first quarter-final between two unseeded players since 2008 (Arnaud Clement v Schuttler), and the Australian said he never felt in control against a tough opponent despite posting a straight-sets win.

"Honestly, I felt I was playing on the back foot a lot, he's a hell of a player, he's obviously feeling very confident, it's been a hell of a tournament from him to make the quarter-finals," he continued.

"I felt I got a bit lucky on a couple of break points here and there, it could easily have been him standing here.

"I'll just take that and prepare for my next match.

"I don't want to think about the semi-final just yet, there's a lot to be done from now until then. We'll go back, my dad will cook dinner as always, we'll watch a movie and just chill out. That's it."

The 27-year-old Australian needed five sets to make it past the 20-year-old American, eventually winning 4-6 6-4 7-6 (7-2) 3-6 6-2.

In a match that was far from smooth sailing, Kyrgios needed a medical timeout following the first set to deal with some shoulder discomfort that has flared up since his fiery win against Stefanos Tsitsipas.

Speaking to the media after his success, Kyrgios said everyone is dealing with niggling injuries this deep into a grand slam, but he is proud of the way he has handled adversity this time around.

"I woke up after Tsitsipas and had some shoulder pain," he said. "I’ve played so much tennis over the last month and a half that I felt it was about time for my body to start feeling some niggles. 

"I don’t think anybody is feeling 100 per cent at this time, Rafa – you see him dealing with something all the time – so it’s something I just manage. Mentally, I think I deal with these things a lot better now. 

"I knew today I wasn’t feeling 100 per cent, but mentally I stayed quite calm, knowing that I wasn’t able to serve full out for the five sets."

His ability to fight through his injury was just one aspect of how Kyrgios feels he has grown as both a player and a person, touching on how far he has come since being dragged out of the pub by his manager in 2019.

"I feel like I’ve been through so much, now I can stay composed," he said. "It’s the first time in my career that I wasn’t playing well, but I was able to say ‘wow, look how far I’ve come’ – It was rewarding. 

"I think I’m enjoying the battle a bit more – I’m expecting everyone to play well against me now. I was that kid once, the underdog, whereas today walking on Centre Court being the favourite was completely different for me, but I was able to navigate that.

"There was a time when I was having to be forced out of a pub at 4am to play Nadal [in the second round of 2019] – my agent had to come and get me out of a pub at 4am before I played my match on Centre Court, Wimbledon. 

"So I’ve come a long way, that’s for sure… to sit here, quarter-finals at Wimbledon, feeling composed, mature, completely blessed and comfortable in my own skin."

Having burst onto the scene at such a young age, Kyrgios said he feels he helped pave the way for the current generation of young stars.

"This is almost my 10th year on Tour," he said. "I kind of feel like I was the first guy who broke through young, like at 19, beating Rafa at Wimbledon. 

"I was the first young guy to show all the other guys – like Zverev and Thiem and stuff – that they could do it as well, I feel like I was the first one to break the mould. You look at guys like Alcaraz, Sinner who are just absolutely fearless. 

"I think a lot of players think that Federer, Djokovic and Nadal are almost Gods and you can’t hurt them. I feel like I showed at least one of them was human that day."