Fourteen-time Grand Slam winner Rafael Nadal has reportedly refused to play doubles with Australian bad boy Nick Kyrgios at a tennis charity event in the US.

Nadal and Kyrgios were originally scheduled to face off in the singles at the John McEnroe Tennis Academy event, but Kyrgios was replaced by fellow Aussie Lleyton Hewitt.

McEnroe, who spoke out on Kyrgios’ behaviour for the first time this week, then partnered Kyrgios in the doubles, taking on Patrick McEnroe and Jonas Bjorkman.

Kyrgios made headlines after an on-court incident in Montreal where he told Stan Wawrinka that fellow Aussie Thanasi Kokkinakis had “banged” his girlfriend, prompting Nadal to comment.

“It is completely unnecessary,” Nadal said during the Montreal tournament.

“It is out of what a tennis match should be.

“Age is not an excuse. It’s just about respect. He was wrong.’’

Tennis great John McEnroe has offered his advice to troubled Aussie Kyrgios.

McEnroe has since told press that he believes Kyrgios should look to Nadal’s on court attitude as an example, but added that he believes the young Aussie has charisma.

"I think he'd be well-served to look at the guys like (Rafael) Nadal, the guys that go out there, tremendous effort players," McEnroe said.

"He can't afford to waste as much energy as he's wasting with these sort of off-court comments ... He's tremendously talented. He's charismatic.

“He's got a look that's different. He brings something to the table."

Kyrgios, who won his doubles match with McEnroe, responded to one question about the incident after the match.

“It’s over now,” Kyrgios said.

“It’s part of the journey. I don’t think anyone was perfect when they were 20.

“It wasn’t the best thing. But I learned from that and keep maturing every day.”

Donna Vekic, who was the subject of Kyrgios’ comments, has blasted tennis authorities for their handling of the controversy.

After breaking down during a qualifying match for the US Open, Vekic launched a furious tirade at the punishment the ATP handed down to Kyrgios for his infamous sledge towards Wawrinka.

The ATP imposed a suspended 28-day ban and A$34,280 fine which can be invoked if the hot-headed, loose-lipped Australian transgresses again.

"He didn’t get suspended," Vekic told the New York Post.