Nick Kyrgios' quest for a first grand slam title at the US Open ended with a five-set quarter-final defeat by Russia's Karen Khachanov.
After reaching the Wimbledon final, Kyrgios arrived in New York motivated to try to go one better but he was unable to find the same tremendous level he showed in beating defending champion Daniil Medvedev in the fourth round.
Instead it is Russian Khachanov who progresses to a first slam semi-final after clinching a 7-5 4-6 7-5 6-7 (3-7) 6-4 victory just before 1am.
Having congratulated Khachanov, Kyrgios showed his frustration with the result by destroying two rackets and then walking swiftly off court.
Kyrgios and Khachanov were tied at 1-1 in their previous meetings on the court while, off the court, they were involved in a Twitter spat two years ago over player behaviour during the coronavirus pandemic, with Kyrgios labelling his rival an "absolute pelican".
After the high of his performance against Medvedev on Sunday, Kyrgios looked a little flat in the early stages of this contest.
He took a medical timeout after losing the opening set for treatment on his left knee, having complained to his box that he could not walk.
The Australian roused himself to take the second set and it was clear the third was crucial in determining how the match would go.
Kyrgios had two chances to break at 4-4 but could not take either, hurling his racket angrily after the second.
Khachanov missed a glorious chance to break in the next game with Kyrgios losing focus, but he shanked a forehand wide from on top of the net.
However, more chances arrived in the next Kyrgios service game and this time the Russian converted, leaving his furious opponent to rant at his box and earn a warning for unsportsmanlike conduct after slamming a drinks bottle on the ground.
The 27-year-old has already been fined a total of $18,500 for four separate offences this tournament, including spitting, swearing and smashing his racket.
Kyrgios was staring down the barrel late in the fourth set but then pulled out a brilliant tie-break to force a decider.
The crowd were firmly on Kyrgios' side but Khachanov was determined not to let his opportunity slip away and broke serve in the opening game.
Kyrgios pressed hard to get back on level terms but Khachanov, ranked 31, resisted all the way to the finish line to set up a semi-final clash with Casper Ruud, who defeated Matteo Berrettini earlier to reach his first US Open semi-final and increase his hopes of becoming world number one.
Fifth seed Ruud saved two set points in the third set on his way to a 6-1 6-4 7-6 (7-4) victory over Italian Berrettini under the roof on Arthur Ashe Stadium.
The French Open finalist must make the final to have a chance of pipping Rafael Nadal to top spot in the rankings and if he were to meet Carlos Alcaraz for the trophy, the winner would also become world number one.
The Norwegian is certainly well in the mix to win his first grand slam title, with defeats for Nadal, Daniil and Marin Cilic in the fourth round meaning there will be a new men's major champion.
Ruud said of the ranking: "I don’t want to think too much about it. It’s of course something that all young players dream about. Let’s see if I can accomplish it.
"Of course it’s a little bit of extra motivation to dig in. If I’m very, very lucky, I can leave New York as world number one."
Ruud initially found success on clay but has turned himself into an all-court player, with his powerful forehand, consistency and athleticism his main strengths.
He dominated Berrettini in the early stages, sweeping into a 6-1 5-1 lead before the Italian rallied and made a fight of the second set.
Berrettini then led 5-2 in the third and had two set points but Ruud hit back and dominated the tie-break to book his place in his second slam semi-final.
The 23-year-old said: "It was a better start than I ever had before in a match, everything was going my way. I was able to take care of the chances that I got.
"I got a little bit nervous towards the end of the second set because things were almost going too well. Sometimes you can get a little bit excited and think that you can walk on water. I managed to serve out the second set and the third was very tough."
Berrettini was disappointed with his performance, saying: "I think he had the best start possible, and I helped him. He played a really good match, and I played a really bad match.
"Really nothing I can say more than the worst day of the tournament probably in the most important moment. I fought through but it wasn't enough. I wasn’t feeling my game. I wasn’t feeling my mindset. I think he was feeling really good."
