Nick Kyrgios said it "f****** sucks" to have exited the US Open due to a hip injury, after John McEnroe criticised him for not training enough.
World number 16 Kyrgios took the first set in his third-round match against Illya Marchenko at Arthur Ashe Stadium, before the problem which forced him to withdraw from the Citi Open in July and continued to trouble him in his first two matches in New York resurfaced.
At the end of the third set, and trailing 4-6 6-4 6-1, the Australian, who does not have a coach, opted to pull the plug on the match.
His decision prompted criticism from ESPN commentator McEnroe, who said: "Nick Kyrgios, if you don't want to be a professional tennis player, do something else. He's hurt because he's not training enough."
Kyrgios stated it was a disappointment to have been forced to withdraw from the competition prematurely.
"Not the way I wanted to end the last grand slam of the year. F****** sucks. #liveandlearn," he posted on social media.
"It's only a failure if you don't learn the lesson."
In his post-match media conference, Kyrgois confessed he needs to focus his attention on additional work away from the court to avoid such injuries.
He said: "It's tough. I don't like to retire. It's probably like the second or third time I've done it.
"It's never easy, of course. I've got a lot of belief in my game to still win matches when I'm not feeling great.
"My hip was bothering me my first two matches and I got through. I guess it was just a matter of time.
"It's almost just hard mentally to play with something like that.
"I got to take more time and be more diligent with, you know, gym and everything so this doesn't happen to me."