Nick Kyrgios critical of fans after being booed off court at Shanghai Masters

Kyrgios was fined at last year's Shanghai Masters for a foul-mouthed outburst

Nick Kyrgios responded to fans who booed him at the Shanghai Masters by saying: "I don't owe them anything."

The Australian patted the ball over the net several times when serving as he lost 6-3 6-1 to German Mischa Zverev.

He also began walking back to his chair before a serve from qualifier Zverev had landed, argued with a fan and received a code violation for swearing.

It came a day after the 21-year-old said he was "bored" during his first-round victory over Sam Querrey.

Kyrgios admitted he "took the easy way out" and "tapped out a little bit" against Zverev in their second-round match, but said the crowd were wrong to criticise him.

"I feel like if they knew what they were talking about they'd be on the tennis court and being successful," he said.

"I can't really understand it at all. They don't know what I'm going through.

"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?"

Kyrgios also said he "couldn't care less" if he reached the season-ending ATP World Tour Finals in London, which features the top eight players in the world.

Kyrgios later adopted a more contrite tone on Twitter

Murray offers Kyrgios advice

World number two Andy Murray said it was Kyrgios' job as a professional athlete to perform at his best in every match.

"He had a great week last week and it is not easy to back it up in a different city the following week if you are feeling a bit tired and jaded," said the Briton, who reached the third round in Shanghai with a 6-3 6-2 win over American Steve Johnson.

"But obviously you have to give your best effort of what you have on that day, that is your job as a professional athlete.

"If you are feeling sick, maybe you are not going to play well or perform as good, but you have to give your best with what you have on the day.

"That is something I have been trying to do in the last few years of my career, accepting when you are not feeling good, maybe a little bit stiff or sore, or a little bit down, you just have to try to push through it."

Kyrgios is ranked 12th in the world after winning the Japan Open on Sunday.

It is the highest ranking he has reached in a career in which he has fallen foul of the tennis authorities for his behaviour.

Last year he was fined $1,500 for a foul-mouthed outburst while playing in Shanghai.

That came two months after he was given a suspended 28-day ban for making a sexual comment about Stan Wawrinka's girlfriend during a match.

Earlier this year, his attitude was questioned after he lost convincingly to Andy Murray in the fourth round at Wimbledon.