Chinese fans boo Nick Kyrgios during listless performance

Nick Kyrgios was booed during a listless 6-3, 6-1 loss to Mischa Zverev at the Shanghai Masters on Wednesday, then angrily defended his behaviour by saying he didn't owe the spectators anything and fans could "just leave" if they didn't like his attitude.

The Australian player, who is known for fiery outbursts and argumentative behaviour on court, put in little effort in the second-round match — just three days after winning the Japan Open in Tokyo.

Kyrgios tapped a soft serve over the net and started walking toward his chair before Zverev had even returned the ball. He floated other first serves in at 67 mph (108 kph) and smacked second-serve faults at 130 mph (210 kph).

Kyrgios hit a risky trick volley between his legs — and still managed to win the point. On changeovers, he bypassed his chair and waited impatiently to serve, twirling his racket on his fingers.

Chair umpire Ali Nili admonished Kyrgios for his behaviour in the first set, saying, "This is a professional tournament, you have to act like a professional."

Toward the end of the 48-minute match, the crowd started booing and jeering. One man yelled, "Respect the game," prompting a furious reaction from Kyrgios, who shouted, "You want to come here and play?"

Asked after the match if he thought he owed the spectators a better effort as one of the stars of the game, he turned defiant again.

"What does that even mean? I'm good at hitting a tennis ball at the net. Big deal. I don't owe them anything," he said. "If you don't like it, I didn't ask you to come watch. Just leave."

On his soft serves, he replied flatly, "My arm was a little sore."

Mentally drained

Kyrgios admitted he didn't put forth his best effort and was mentally drained after winning his third title of the season in Tokyo.

"I guess that's why I'm trying to work on being able to be consistent every week," he said. "Just took the easy way out tonight and obviously didn't show up at all."

Zverev joked about some of Kyrgios' serves after the match — it felt like the last time he played his girlfriend, he said — but he also defended the Australian and said he shouldn't be criticized for his professionalism.

"Would Federer behave like that? Probably not," Zverev said. "But [Kyrgios] has a creative mind. ... He's top-15, 16 in the world so he's doing something right."

Zverev also said it's normal to be fatigued at the end of a grueling season.

"You reach a point where you're mentally tired and some people react one way, some people react a different way," he said. "It doesn't say anything about whether he's professional or not."