McEnroe, Laver lead criticism of Nick's meltdown

Tennis greats are slamming the behavior of Aussie bad boy Nick Kyrgios after yet another inexplicable meltdown triggered his spectacular early exit from the Australian Open on Wednesday.

The combustible 21-year-old was booed off the court and accused of giving up as he crashed out in the second round in a stormy five-set loss to Italy's Andreas Seppi, despite winning the first two sets.

On Thursday, the world No 13 pulled out of the doubles competition, citing an injury, and was slapped with $5,500 in fines for swearing and throwing his racket during the loss to Seppi.

Former superstar-turned - pundit John McEnroe labeled Kyrgios as "mentally (ranked) about No 200 in the world" and giving the sport a "black eye", while the legendary Rod Laver criticized his compatriot's bizarre antics.

The latest episode in the tempestuous career of Kyrgios comes as he makes his return from a ban for "lack of best efforts" - commonly known as tanking - during an October match in Shanghai.

He has since been seeing a psychologist.

After being penalized and fined for throwing his racket in the third set, Kyrgios unraveled and started playing casually and lethargically, unnecessarily hitting a 'tweener' shot between his legs.

The tennis world remained incredulous on Thursday over yet another example of Kyrgios' volcanic self-destruction from a winning position, but McEnroe was particularly damning.

"Even I'm at a loss for words," said the American.

"Overall I would call it a damn shame because I think he's the most talented guy in the world (aged) 21 and under - maybe even at 29 and under," McEnroe said during television commentary on ESPN.

"He could be the best player in the world, but mentally he's about 200 in the world, and I think at critical moments it shows.

"When he goes through these periods when he's not competing, then it's just a black eye for the sport. And it's a black eye for him."

Laver, the last player to complete the calendar-year Grand Slam, was more conciliatory but nonetheless took Kyrgios to task.

"He's got a lot of talent, yes, but behavior is part of the game, part of any sport," Laver told the Herald-Sun newspaper.

"I think you've got to be able to represent the game you're playing."

Four-time Grand Slam champion Jim Courier was another who was mystified by the mental state of the wayward star.

"It is amazing how it can go from so much fun for him to so much misery, when he wasn't at peril at all," Courier said during Channel 7 match commentary.

Davis Cup teammate Bernard Tomic said he couldn't believe how Kyrgios had lost the match against Seppi after winning the first two sets.

"Regardless, he's still an amazing player and he's going to be huge in our sport," Tomic said.

The media continues to be fascinated by the confounding Kyrgios.

Melbourne's Herald-Sun headlined, "Kyr Factor Zero - Nick's fine line between madness and genius", while The Australian wrote, "Nick Kyrgios adds to shame file".

As for Kyrgios himself, he said he was struggling with an injury he picked up playing basketball, and admitted he hadn't trained hard enough pre-season.

"I'm disappointed," he said. "I'm OK. I'm alright. You know, the world keeps spinning. I lost one match."