Nick Kyrgios suffered more injury problems as he slumped to a 6-3 1-6 6-4 6-1 loss against fellow Australian John Millman at the US Open.
Kyrgios hurt his right shoulder during the third set and, although he played out the rest of the match, it was to no avail as Millman prevailed in four sets.
Kyrgios was clearly disconsolate at having another physical issue after playing so well in Cincinnati two weeks ago, beating Rafael Nadal before losing to Grigor Dimitrov in the final.
He complained of his right arm feeling dead after hurting it on a serve early in the third set. Kyrgios received treatment and a sympathetic ear from the trainer as he explained his frustration but no solution to his problem.
The Australian angrily protested a code violation given after he swore in frustration at his physical issues.
It was not heard by umpire Carlos Ramos but reported to him by a line judge.
Kyrgios then received a point penalty when, after dropping serve to lose the third set, he smashed his racket violently on the court. But ultimately his main concern was the state of his body.
Talk about not being prepared before the match Kyrgios was playing basketball eating Mister Softee. pic.twitter.com/UdCGVPPltU
— Pseudo McEnroe (@McEnroeTweets) August 30, 2017
Having failed to wedge the broken racket into his bag, Kyrgios walked off court holding it with head bowed and boos ringing in his ears, rather summing up his day.
Asked if he wanted to be more dedicated, Kyrgios said: "Probably not, honestly not.
"In Cincinnati, I was not doing anything different. I was probably less dedicated than I was this week. I was playing basketball every day for two hours.
"I was going to get ice cream, getting a milkshake every day. I was less dedicated. And this week I was dedicated, and my shoulder starts hurting."
As for what he does next, a dejected Kyrgios said: "I don't know. I keep letting people down."
"Obviously I'm disappointed I lost today, but it's not the end of the world. I will get over it in probably half an hour."
Kyrgios looked to have turned a corner earlier this season when he posted a series of impressive results but he has been unable to stay healthy over the past few months.
He aggravated a hip injury at Queen's Club in June and retired during three successive matches, including his opener against Pierre-Hugues Herbert at Wimbledon.
Kyrgios has won just two grand slam matches all season, one at the Australian Open and one in Paris, and he added: "I have had a diabolical year at the slams.
"It doesn't surprise me. It's just the story of my career, really. I will have good weeks; I'll have bad weeks. It's just a rollercoaster.
"Obviously I'm disappointed I lost today, but it's not the end of the world. I will get over it in probably half an hour. I will get food and watch the matches."
Kyrgios' defeat is potentially good news for Roger Federer, who struggled through a five-set win over Frances Tiafoe in round one and could have faced the Australian in the fourth round.
Alexander Zverev's wait for a grand slam breakthrough goes on after the German lost to fellow young gun Borna Coric in the second round of the US Open.
Zverev has established himself as the leader of the next generation and, following Andy Murray's withdrawal, was the highest-ranked player in the bottom half of the draw.
But the fourth seed found himself having to play second fiddle to another 20-year-old as Coric reminded everyone that he was a teenage prodigy too.
The Croatian's progress has stalled over the past couple of years but he was exceptional here, withstanding huge pressure in the fourth set to win 3-6 7-5 7-6 (7/1) 7-6 (7/4).
Elsewhere, there were first-round wins for Grigor Dimitrov, Dominic Thiem, David Goffin, Juan Martin del Potro, Gael Monfils and Tomas Berdych but Richard Gasquet was beaten by Leonardo Mayer.
Nick Kyrgios looks to the ballboy for help after struggling with an injury 😂 pic.twitter.com/JniT5cFyzH
— Eurosport UK (@Eurosport_UK) August 30, 2017
Meanwhile, Kyle Edmund was the only Briton to make it into the third round.
The British number two gained his second straight-sets win of the tournament, defeating American Steve Johnson 7-5 6-2 7-6 (7/4) to book a third-round date with exciting young Canadian Denis Shapovalov.
