Australian Nick Kyrgios admitted he "took the easy way out" after appearing to give up during a 6-3 6-1 defeat to qualifier Mischa Zverev at the Shanghai Masters.
Kyrgios, who won the Japan Open title last week, could face punishment after he was booed off the court during a petulant display that included tame serves and walking out of points before they were finished.
Footage of Kyrgios' behaviour went viral online and across social media.
"It was just tough. Obviously I played a lot of matches in a row. Physically tired, mentally tired," the 21-year-old said in a post-match press conference.
"That's why I'm trying to work on being able to be consistent every week. Just took the easy way out tonight and obviously didn't show up at all.
"I wasn't so much frustrated. I just tapped out a little bit, I guess."
Kyrgios was hit with a code violation for swearing in the first set and was then booed by the crowd as he walked off the court after failing to face a return from Zverev following his own tame serve to trail 4-1.
Sitting in his chair, the world number 14 became involved in a heated exchange with umpire Ali Nili, who told the Kyrgios to "act professional and play with your best effort the whole time".
In the second set, when facing game point at 1-1, Kyrgios started to walk off before Zverev's serve had landed in his side of the court.
Later, when Zverev served at 5-1, the Australian responded to heckling from the crowd before conceding the match when he chipped up a return which allowed the German to put away match point after 48 minutes on court.
WATCH: @NickKyrgios throws game in bizarre Shanghai Masters exit. More here: https://t.co/WjmBNbDJ0n #SSNHQ https://t.co/Vk93AuRRhy
— Sky Sports News HQ (@SkySportsNewsHQ) October 12, 2016
Kyrgios defended his exchange with the crowd, saying: "They don't know what I'm going through, so no, I don't understand it.
"I feel like if they knew what they were talking about they'd be on the tennis court and being successful as well.
"I don't owe them anything. It's my choice. If you don't like it, I didn't ask you to come watch. Just leave.
"If you're so good at giving advice and so good at tennis, why aren't you as good as me? Why aren't you on the tour?
"You want to buy a ticket? Come watch me. You know I'm unpredictable. It's your choice. I don't owe you anything. Doesn't affect how I sleep at night."
Kyrgios could face a battle to make the season-ending ATP World Tour Finals next month, but the Australian claimed he was "couldn't care less" whether he qualified for London.
Kyrgios was more apologetic later wrote on Twitter.
At Wimbledon 2015, Kyrgios suffered a similar on-court meltdown when losing to Richard Gasquet.
Not good enough today on many levels, I'm better than that. I can go on about excuses but there are none. Sorry #StillAWorkInProgress 🙏🏽😢😞
— Nicholas Kyrgios (@NickKyrgios) October 12, 2016
