Novak Djokovic said "I'll take your legs out, that's for sure" after digging deep to outlast American qualifier Jenson Brooksby in a physically demanding encounter at the US Open.

Djokovic – bidding to become only the third man to claim a calendar Grand Slam and first since Rod Laver in 1969 – rallied from a set down to prevail 1-6 6-3 6-2 6-2 en route to the quarter-finals in New York on Monday.

It was a brutal clash on Arthur Ashe Stadium, 20-time major champion and top seed Djokovic needed almost three hours to see off world number 99 Brooksby, who was making his debut at the iconic venue.

After being blitzed in a 29-minute opening set, Djokovic and Brooksby contested a gruelling 20-minute fifth game in the second set – the latter converting a sixth break-point chance.

Djokovic's physical superiority, however, was on display as the Serb star eventually powered past the spirited 20-year-old at Flushing Meadows.

During the last-16 matchup, former world number one Andy Roddick tweeted, in reference to Djokovic, "first he takes your legs… then he takes your soul".

Djokovic – who will face sixth seed Matteo Berrettini in a repeat of the Wimbledon final – said on court: "Thanks Andy, I take that as a compliment – only the first part.

"The second part, I don't take anybody's soul. Everyone has their soul, we're all beautiful souls so I appreciate everyone. But I'll take your legs out, that's for sure."

Djokovic hit 44 winners in the four-set triumph, to go with 41 unforced errors in a tricky clash under the Arthur Ashe lights.

With his hard-fought victory, Djokovic improved to 11-0 against Americans at the US Open. He is 29-3 at major events and 70-10 in ATP Tour-level matches.

The 34-year-old is on a 21-match winning streak against players from the United States since Sam Querrey snapped his 30-match slam streak at Wimbledon in 2016.

"Great quality match," Djokovic, who can break the record for most men's slam titles – currently level with injured pair Rafael Nadal and Roger Federer, told reporters. "He started off better. I've never played him. I didn't see him play too many times. Maybe few matches in the last few months. Haven't followed his career prior to that, so I didn't know much about him. Had to do some homework and some analysis.

"It's different stepping out on the court first time against someone that really has nothing to lose. He's a young, talented player that is very crafty. He's got the really all-around game. He was pumped. He had the crowd behind him, of course. He played a perfect first set. Everything he intended to do he executed it perfectly.

"On my end, I was just trying to find a rhythm, trying to read his game, trying to understand where I can find holes in his game and start to attack and shift the momentum to my side.

"That happened already at the beginning of the second set. I broke him early. He broke back. But I re-broke his serve right away. We had some very, very long rallies, long games. It took a toll physically I think on both of us at that point. But I managed to find the right serves. I served efficiently when I needed to, opening up the court.

"The third and fourth set were really, really good from my side. I felt I was more dominant. I decreased the unforced errors that were really high in the first part of the match. I just was kind of swinging through the ball better. Was a good finish. It wasn't a good start. But all in all, expected the battle, and I got that one. I'm pleased to overcome it."

World number one Novak Djokovic's quest for a calendar Grand Slam and record-breaking 21st major title remains on track after outlasting Jenson Brooksby 1-6 6-3 6-2 6-2 in a gruelling US Open showdown.

Unheralded American qualifier and world number 99 Brooksby had the crowd roaring following an incredible opening set against Djokovic in Monday's last-16 clash at Flushing Meadows.

However, Djokovic – bidding to become only the third man to sweep all four slams in the same year and first since Rod Laver in 1969 – responded to the almighty challenge, showcasing his superior physicality as the three-time US Open champion rallied into the quarter-finals in New York.

Brooksby was making his first appearance on Arthur Ashe Stadium, where the 20-year-old was looking to become the lowest-ranked player to beat a number one at the US Open since the start of the ATP rankings in 1973 and youngest American man since Andy Roddick (2003 Wimbledon) to reach a major quarter-final.

He was not overawed on the big stage, blitzing Djokovic in a remarkable first set. Playing with a bounce in his step and bringing the crowd to its feet, Brooksby only hit one unforced error in a dominant 29-minute display, which included two breaks of serve.

Djokovic was 38-34 at grand slams when losing the opening set and 12-10 at Flushing Meadows and after an error-filled opener, the Serb star let out an almighty roar after racing out to a 3-0 lead.

Just as Djokovic – level on 20 men's slams with Rafael Nadal and Roger Federer – looked comfortable, he endured a marathon 20-minute fifth game against Brooksby.

Brooksby broke at the sixth time of asking and the breath-taking tennis continued as Djokovic broke straight back to reclaim his advantage at 4-2 – the latter ending the game with an intense stare down in the direction of his opponent.

After a gruelling second set to level the match, the third followed a similar pattern, with Djokovic breaking in the opening game before moving 3-0 ahead.

Djokovic did not relinquish that lead, hitting 13 winners while claiming 11 of his 13 points at the net as he took the match to Brooksby.

Brooksby put up a huge fight but, he was unable to maintain his charge as the crowd went silent – Djokovic looking ahead to a last-eight showdown with sixth seed Matteo Berrettini in a rematch of the Wimbledon final.

Data slam: Djokovic flawless against locals in New York

With his hard-fought victory, which lasted almost three hours, Djokovic improved to 11-0 against Americans at the US Open. He is 29-3 at major events and 70-10 in ATP Tour-level matches. The 34-year-old is on a 21-match winning streak against players from the United States since Sam Querrey snapped his 30-match slam streak at Wimbledon in 2016.

WINNERS/UNFORCED ERRORS

Djokovic – 44/41
Brooksby – 27/28

ACES/DOUBLE FAULTS

Djokovic – 9/1
Brooksby – 4/1

BREAK POINTS WON

Djokovic – 6/12
Brooksby – 3/11

Shelby Rogers was anticipating "nine million death threats" after her fourth-round loss to Emma Raducanu at the US Open on Monday. 

Just two days after coming from two breaks down in the third set to defeat world number one and top seed Ash Barty, Rogers succumbed to a 6-2 6-1 defeat at the hands of Raducanu.

The 18-year-old consequently reached the first grand slam quarter-final of her career and became just the third qualifier to reach the last eight of the women's draw at Flushing Meadows in the Open Era.

Having been overwhelmed with adulation in the wake of her win against Barty, Rogers admitted she was now concerned the scales would tip the other way. 

Sloane Stephens revealed she received more than 2,000 abusive messages on social media after losing to Angelique Kerber in the third round and her fellow American was wary of suffering a similar fate. 

"I kind of wish social media didn't exist, but here we are. It's a big part of marketing now. We have contracts, we have to post certain things," said Rogers. 

"You could probably go through my profile right now, I'm probably a fat pig and words that I can't say right now. But, I mean, it is what it is. You try not to take it to heart, and it's the unfortunate side of any sport and what we do." 

She continued: "I think someone asked by the other day some advice I would give, and I said try not to get too high or too low with every match. 

"It's tough when you know you have a win like that [against Barty] and everybody is treating it like the final. Everybody coming up to me on-site. 

"I'm really actually happy I had doubles [on Sunday] because it kind of refocused me a little bit, but everyone's coming up to you, 'Oh, great win.' I'm like, 'Yeah, but it's just the third round. We're not even halfway right now.' 

"It's just really tough sometimes to keep that in perspective, but you do the best you can and try to ignore the media and everybody blowing it up and making you the story of the tournament. 

"Obviously, we appreciate the spotlight in those moments, but then you have today and I'm going to have nine million death threats and whatnot. It's very much polarising – one extreme to the other very quickly. 

"At this point in my career, I'd say I'm used to it. It's just now for me, finding a way to have those big wins but then be able to back it up a little bit. It's not easy to say the least." 

Rogers won just 38 per cent of points behind her first serve and committed a total of 29 unforced errors, leaving the 28-year-old hugely dissatisfied with her display. 

"That was pretty embarrassing," she said. "It was a tough day at the office. Unfortunately, I had to fail in front of thousands and thousands of people. I have to live with that one. 

"It's disappointing that I couldn't must up a little more today. But I told you guys the other night it took everything I had to beat Barty. I guess that was a little apparent today. The tank was empty."

Emma Raducanu broke new ground on Monday as the qualifier reached the quarter-finals of the US Open in supreme style.

The 18-year-old produced one of the performances of the tournament when she defeated Sara Sorribes Tormo 6-0 6-1 on Saturday.

The Briton lost the first two games of her clash with Shelby Rogers, who impressively beat world number one Ash Barty in the previous round, but she then stormed to a 6-2 6-1 victory in her first outing on the court of Arthur Ashe Stadium.

Raducanu, who made headlines in the United Kingdom when she reached round four on her Wimbledon debut in July, will now face Olympic gold medallist Belinda Bencic in the first major quarter-final of her career.

Raducanu responded after a nervy start by reeling off six games in a row to take the first set in dominant fashion.

Rogers, who won just 12 points behind her first serve throughout, seemed to wilt against the onslaught as her groundstrokes became wild, her unforced error count totalling 29 by the end.

Raducanu appeared to feel the nerves towards the end of the second set but eventually closed out a famous win on her fourth match point, becoming just the third qualifier in the Open Era to reach this stage of the US Open.

"It feels absolutely amazing to play in front of all of you," she said in her on-court interview. "I'm so happy to have come through and overcome some of the nerves from the beginning.

"Belinda's a great player who's in great form, so I know I'm going to have to bring it.

"I'm just not really thinking about tennis right now. I'll leave that for tomorrow!"

Raducanu will face Bencic on Wednesday, the Swiss having beaten seventh seed Iga Swiatek in straight sets.

Carlos Alcaraz's fairytale run to the quarter-finals at the US Open is a dream come true for the Spanish teenager.

Alcaraz became the youngest men's US Open quarter-finalist in the Open Era when he ousted Peter Gojowczyk 5-7 6-1 5-7 6-2 6-0 on Sunday.

The 18-year-old, who became the youngest man to defeat a top-three player at Flushing Meadows when he beat Stefanos Tsitsipas last week, is also the most junior male player at the New York grand slam since Thomaz Koch in 1963.

Similarly, Sunday's triumph made him the youngest men's singles quarter-finalist at any grand slam since Michael Chang (18) made the last eight at the 1990 French Open.

Alcaraz will now face another rising star – Felix Auger-Aliassime – for a place in the semi-finals.

"I'm super excited to be in my first second week in the grand slam, so it's amazing for me. It's a dream come true," an ecstatic Alcaraz told reporters.

"It's really tough to play these kinds of matches, to play fifth sets. I hope to play [in] more second weeks, to play more quarter-finals of grand slams.

"I didn't expect to play in the quarter-finals here, so I think it's a really good performance from me in these matches."

Dubbed as the heir to Rafael Nadal's thrown, Alcaraz has certainly had the crowd on his side during his run.

"In the first sets I thought that I reached my limit, physically and mentally. I think the crowd was really, really important for me in this situation," Alcaraz added.

"I felt the energy of the crowd pushing me up. I think without the crowd, it couldn't be possible to be here."

Alcaraz faces a stern test in the form of world number 15 Auger-Aliassime, who has reached his second straight grand slam quarter-final.

However, the 21-year-old Canadian – who is aiming to secure a maiden appearance in the last four of a major – knows the quality Alcaraz possesses.

"He's a great player. At some point age is just a number. He already feels like a player who's established," Auger-Aliassime said of Alcaraz.

"He's playing some amazing tennis, so I think we’ll see a lot of him, a lot of us, a lot of Frances [Tiafoe] in the future."

Teenage Spanish sensation Carlos Alcaraz made history after outlasting Peter Gojowczyk for a US Open quarter-final berth.

Alcaraz became the youngest men's US Open quarter-finalist in the Open Era thanks to Sunday's 5-7 6-1 5-7 6-2 6-0 victory at Flushing Meadows.

After stunning third seed Stefanos Tsitsipas in New York, where he became the youngest man to defeat a top-three player at the US Open, the 18-year-old needed another five-setter to continue his fairytale run.

Alcaraz rallied past Gojowczyk, finishing with 35 winners – five more than the German qualifier – and 45 unforced errors, which were 39 fewer than his opponent.

Dubbed the new Rafael Nadal, Alcaraz became the youngest men's US Open quarter-finalist since Thomaz Koch (18) in the pre-Open Era in 1963.

He also became the youngest men's grand slam singles quarter-finalist since Michael Chang (18) at the 1990 French Open.

With the win, Alcaraz became the youngest men's player to earn back-to-back five-set wins at a grand slam since Chang (16) at the 1988 US Open as Felix Auger-Aliassime or Frances Tiafoe await.

Canadian sensation Leylah Fernandez said she is pinching herself after continuing her fairytale run with a shock last-16 win over Angelique Kerber at the US Open.

After stunning defending champion Naomi Osaka in a third-round boilover at Flushing Meadows, giant-slaying teenager Fernandez conquered three-time grand slam winner Kerber 4-6 7-6 (7-5) 6-2 en route to the quarter-finals.

Kerber – the 2018 US Open champion – won the opening set in New York, however 18-year-old Fernandez staged a remarkable comeback on the eve of her 19th birthday to reach her first slam quarter-final.

"I did have to pinch myself a little bit to see that it actually happened, but like I said, I knew that my tennis, my level of tennis is there," Fernandez said post-match. "It's just a moment of time, opportunity, and I'm glad that I was able to get this opportunity now and that I was able to showcase what I can do in front of these players.

"Even if I would have lost, I would have been proud of myself with the way that I played, the way that I fought. I was lucky enough to get the win today and just getting this experience.

"It's my first fourth-round quarterfinals in a grand slam. I'm just going to enjoy it at 100 per cent, and tomorrow is going to be a new day."

Fernandez, who hit 45 winners to 34 unforced errors – added: "The match was incredible. I was playing well in the first set.

"Unfortunately I did a few mistakes. Her, as a great player, great champion, she noticed and she took advantage of it. I was able to refocus and fight back for the second.

"In the third, I was just enjoying every moment of it. Honestly, the crowd has been amazing, so thanks to them I was able to win."

"I'm just super happy," she continued. "I'm going to enjoy tonight as much as I can, and then once I'm off to bed, I'll try to forget about it so that I can get ready for tomorrow."

Daniil Medvedev said "it's tough to beat me" as the confident and in-form world number two took another step towards his maiden grand slam crown at the US Open.

Medvedev advanced to the quarter-finals with a comfortable 6-3 6-4 6-3 victory over 24th seed Dan Evans in New York on Sunday.

US Open finalist in 2019 and Australian Open runner-up this year, Russian star Medvedev is yet to drop a set at Flushing Meadows this week.

As Dutch qualifier Botic Van De Zandschulp awaits, Medvedev discussed expectations at the US Open in pursuit of his first major title.

"I always say I take it match by match," Medvedev told reporters after hitting 42 winners in one hour, 43 minutes. "You can lose first round, you can lose final. If I play good, I know what I'm capable of. It's tough to beat me.

"In Wimbledon, I was honest, I lost against a great player, Hubert is playing great. I think he's on the rise. He's going to be even better ranked and maybe he's gonna go further in slams. He beat Roger [Federer] after me.

"But again, I was not talking about match itself where the loss was okay, I would say. I was talking about the result in general, and fourth round is not enough for number two in the world, especially I like grass more than clay, so maybe on clay I would not say this.

"Yeah, it's the same every tournament. If you're top seed, if you are not in the final, let's say Cincinnati, I lost against Rublev, brutal match, really strong play from him. But if you talk about the result itself, semi-final was not good enough.

"There is not much to add. I want to win every tournament I play in, without putting pressure on myself. Because again, I know how to win matches, and I know sometimes why I lose them, so that's just learning and being better for the next time."

Medvedev is 31-5 on hard courts in 2021 and 162-61 in his career, while he has won 11 of his 12 ATP titles on hard courts.

The 25-year-old owns a 17-4 record (80.95 per cent) at the US Open – his most wins and highest win percentage at a grand slam event.

"Feeling great before the second week," Medvedev said. "Feeling great with my tennis, my mental, my physical. Just looking forward."

Medvedev, who lost a thrilling US Open final to Rafael Nadal two years ago, added: "Now I just want to make it to the finals again to have another thing to remember and hopefully a better one."

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."

Novak Djokovic powered through to week two of the US Open by sinking Kei Nishikori, a player who must be sick of the sight of the Serbian.

For a 17th consecutive time in their rivalry, Djokovic beat the former world number four, who was runner-up at this tournament seven years ago.

A 6-7 (4-7) 6-3 6-3 6-2 victory in three hours and 33 minutes for Djokovic moves him into the fourth round, ever closer to the calendar Grand Slam he is chasing, having already won the Australian Open, French Open and Wimbledon.

Nishikori beat Djokovic in the US Open semi-finals in 2014, before losing to Marin Cilic in the final, but that was the last time he got the better of the man from Belgrade.

Djokovic won their 2018 semi-final at Flushing Meadows for the loss of just nine games and a 6-2 6-0 win for the world number one over Japan's Nishikori at the Tokyo Olympics in July suggested this latest clash in New York, the 20th between them, could be similarly one-sided.

Yet it became clear early in this clash that Djokovic faced a substantial test. He trailed 4-2 in the opener and could not save the set, despite forcing a tie-break. A stunning lob from Nishikori gave him two serves for the set, and he held his nerve to move in front.

Djokovic broke in the third game of the second set though and staved off a flurry of break-back points on his way to levelling the match.

When Nishikori served a double fault to allow Djokovic two break points in game four of the third set, it was inviting trouble. Djokovic won the second of those when his low slice and net rush prompted Nishikori to net a backhand.

Against the flow of the match, Nishikori broke back, helped by two consecutive double faults, but order was restored as Djokovic rolled through the next two games to move a set away from the next round.

Nishikori probably needed Djokovic's body to fail him, or for something as bizarre as last year's disqualification to occur, but nothing of the sort happened in set four, the world's best player in a class of his own.

Djokovic said: "I don't think I started off very well. I was too passive and too far back in the court and he was dictating the play. It took me a little bit of time to adjust to his game.

"By the beginning of the second set I felt like I was getting my groove back, getting my rhythm back. I was very pleased with my focus."

DATA SLAM

Nishikori will look back to the second set and ponder 'what if?', because he had seven break points and took none of them. Djokovic had three in that set and took two, and there lies greatness. Tennis comes down to taking chances as they arrive, being clinical, and after the chaos of the first set this was a ruthless Djokovic show.

WINNERS/UNFORCED ERRORS

Djokovic – 45/52
Nishikori – 38/56

ACES/DOUBLE FAULTS

Djokovic – 15/7
Nishikori – 6/3

BREAK POINTS WON

Djokovic – 7/16
Nishikori – 2/13

Sloane Stephens has detailed the online abuse she received after exiting the US Open to Angelique Kerber.

Stephens, who won at Flushing Meadows in 2017, was beaten 5-7 6-2 6-3 in the third round on Friday by three-time major champion Kerber.

The American had defeated outstanding teenager Coco Gauff in her previous match but could not maintain a title challenge in New York.

It was a defeat that prompted a shocking response on social media, Stephens revealed on Saturday.

"I am human," she wrote on her Instagram story. "After last night's match I got [more than 2,000] messages of abuse/anger from people upset by yesterday's result.

"It's so hard to read messages like these, but I'll post a few so you guys can see what it's like after a loss..."

Stephens then shared screenshots of a series of threatening, racist and misogynistic messages aimed in her direction.

She added: "This type of hate is so exhausting and never ending. This isn't talked about enough, but it really freaking sucks...

"I'm happy to have people in my corner who support me. I'm choosing positive vibes over negative ones.

"I choose to show you guys happiness on here, but it's not always smiles and roses."

Emma Raducanu came within one point of a sensational double bagel against Sara Sorribes Tormo and could face Ash Barty next at the US Open.

The 18-year-old Briton came through qualifying to make her Flushing Meadows bow this week.

And now Raducanu is remarkably into week two without dropping a set.

She saved her best performance yet for round three, winning 6-0 6-1 after passing up a match point on Sorribes Tormo's serve that would have sealed a flawless result.

Her place in the fourth round was a fine consolation for Raducanu, who reached the same stage at Wimbledon in July, then appearing in a grand slam main draw for the first time.

A match against Ajla Tomljanovic proved a step too far at the All England Club, but Raducanu may now get an opportunity to advance against another Australian.

If Barty beats Shelby Rogers later on Saturday, the world number one will face Raducanu next week – presumably far away from the Court 17 the teenager was consigned to on this occasion.

Given Sorribes Tormo beat Barty in straight sets in the first round of this year's Olympic Games, Raducanu should have nothing to fear.

"It's been two weeks in New York now," she told Prime Video. "And into the third week – I never thought I'd be here, but I'm just so, so excited."

Raducanu said of her latest triumph: "I was playing very well. I know Sara is an extremely tough opponent – she doesn't make a mistake, so you have to be on your game every single point.

"I had to work so hard, and there were some really, really long deuce games that could have gone either way, so I'm just really happy that I managed to maintain and stay on it and win in the end."

It was a far more comprehensive success than Raducanu was willing to admit, though, with the world number 150 having 11 break point opportunities to her opponent's zero.

Raducanu's blistering forehand averaged 92 miles per hour on serve, while she played 23 winners.

"Honestly, for this one, the plan was I had to hit through her, I had to hit the corners," she added. "If you trade against her, you're probably going to come out second best.

"I just took the game to her and hit more winners than errors today."

Leylah Fernandez revealed how the energy of the Flushing Meadows crowd helped power her to a stunning comeback win over Naomi Osaka at the US Open. 

Reigning champion Osaka appeared on course to progress when up a set and serving for the match at Arthur Ashe Stadium, only to let the opportunity slip away. 

The world number three lost her serve and then also her composure in the tie-break that followed, throwing her racquet on more than one occasion as Fernandez prevailed to force a decider. 

The Canadian teenager broke immediately at the start of the third set and retained that advantage through to the finish, allowing her to complete a famous victory in New York. 

"I wasn't really focused on Naomi, I was focused on my game and what I needed to do," Fernandez told the media. 

"Having the crowd there, supporting me, backing me up after every point, it was amazing. It gave me the energy to keep fighting, keep working, keep running for those balls that she hit.

"I was just glad that I was able to put on a show for everyone who came to watch."

The 18-year-old also explained how she has always had a competitive streak, adding: "From a very young age, I knew I was able to beat anyone who was in front of me.

"Even playing different sports, I was always that competitive and saying I was going to win against them, win against my dad in soccer, even though that was impossible, I've always had that belief, tried to use that in every match when I go on. I guess today that belief came true."

Osaka announced in her post-match media duties that she plans to "take a break from playing for a while", as well as apologising for her outbursts on court.

She received a warning for hitting a ball into the stands but appeared set to launch a fightback of her own in the deciding set, only for the impressive Fernandez to hold firm.

"I've watched her win the US Open, I've watched her win the Australian Open the very next year – just seeing her, learning from her, has helped shape my game," Fernandez said of Osaka.

"She is a great example for anybody on Tour, and all the little girls in the world.  

"I'm just glad I had the opportunity to play against her, show everyone I am also able to compete against the best players out there."

Naomi Osaka's short-term future appears away from the tennis court after the tearful former world number one said she plans to "take a break from playing for a while" following her shock US Open elimination.

Osaka's US Open title defence came to a remarkable end after imploding in Friday's surprise 5-7 7-6 (7-2) 6-4 loss to teenage sensation Leylah Fernandez.

Up a set and serving for the match at 6-5 on Arthur Ashe Stadium, Osaka lost her cool and composure after throwing her racquet three times in an unsuccessful second-set tie-break.

Amid boos in New York, Osaka was also warned after hitting a ball into the crowd and while the four-time major champion tried to dig herself out of a hole, she crashed out in incredible fashion.

It comes following a difficult couple of months due to mental health concerns as a result of "long bouts of depression" since winning the 2018 US Open.

Osaka withdrew from May's French Open having won her first-round match, after she was fined and threatened with further punishment – and possible expulsion from the grand slam – for skipping obligatory media duties.

The Japanese star subsequently pulled out of Wimbledon before returning for the Olympic Games, though she suffered a surprise loss on home soil in Tokyo and was reduced to tears during a news conference in Cincinnati.

During an emotional post-match news conference, Osaka told reporters: "I'm going to say what we said, I think, like, in the hallway. How do I go around saying this?

"I feel like for me recently, like, when I win I don't feel happy. I feel more like a relief. And then when I lose, I feel very sad. I don't think that's normal. I didn't really want to cry.

"I feel like… this is very hard to articulate. I feel like I'm kind of at this point where I'm trying to figure out what I want to do, and I honestly don't know when I'm going to play my next tennis match [tearing up]. Sorry."

Osaka – who was bidding to become the first woman to defend the US Open since Serena Williams in 2014 – added: "I think I'm going to take a break from playing for a while."

Typically reserved and quiet, Osaka was uncharacteristically frustrated on court – the 23-year-old immediately left the court and emerged with a towel over her head before the start of the final set.

On her outburst, Osaka said: "I'm really sorry about that. I'm really sorry about that. I'm not really sure why.

"I was telling myself to be calm, but I feel like maybe there was a boiling point. Like normally I feel like I like challenges. But recently I feel very anxious when things don't go my way, and I feel like you can feel that. I'm not really sure why it happens the way it happens now.

"It's basically why. You could kind of see that. I was kind of like a little kid."

Carlos Alcaraz was lost for words after making history in the Spanish teenager's shock five-set upset of world number three Stefanos Tsitsipas at the US Open.

Alcaraz – rated by many as Spain's best young male player since 20-time grand slam champion Rafael Nadal first emerged – sent Tsitsipas packing 6-3 4-6 7-6 (7-2) 0-6 7-6 (7-5) in the third round on Friday.

The 18-year-old Alcaraz became the youngest player to reach the last 16 of the US Open since Americans Michael Chang and Pete Sampras in 1989.

Alcaraz also became the youngest man to beat a top-three opponent at the tournament since the ATP introduced its world ranking system in 1973.

After more than four hours on Arthur Ashe Stadium, Alcaraz told reporters: "I have not words to explain how I feeling right now.

"I just don't know what happened out there in the court. I can't believe that I beat Stefanos Tsitsipas in an epic match.

"For me it's a dream come true."

Amid comparisons with countryman Nadal, Alcaraz added: "Honestly I don't copy any style of a players. I just play my game.

"But if I have to say one player that is similar my game, I think it's [Roger] Federer. I think similar as mine game, trying to be aggressive all the time. I think it's a good similar for me."

After his US Open campaign came to a surprise end, third seed Tsitsipas tipped Alcaraz for future success.

"A hundred percent," Tsitsipas replied when asked if he had a sense of Alcaraz's potential. "I said he can be a contender for Grand Slam titles. He has the game to be there."

"I've never seen someone hit the ball so hard," French Open runner-up Tsitsipas added. "Took time to adjust. Took time to kind of develop my game around his game style.

"It's one of these matches and one of these feelings where, you know, you pick up at some point of the match, you feel like you're in control, and it doesn't really go your way at the end.

"It's kind of bitter, I would say, especially after such an incredible first set by my side, dominating, being just so aggressive, not dwelling on the past. It was a great first set.

"I don't know. I felt like he played the fifth one completely -- the way he played the first set basically, careless, going for every single shot. I have never seen someone play such a good fifth set, honestly."