Australian tennis legend Rod Laver has warned Nick Kyrgios must change to realise his potential as a champion.

“His mouth and his antics have taken over and unfortunately you can’t get anywhere being this way,” said Laver.

“You’ve got to be able to concentrate on the match at hand.”

Laver’s comments came after fellow great John McEnroe slammed Kyrgios for “bonehead” low-percentage shot selection in his US Open first round loss to Andy Murray.

Laver said Kyrgios possessed huge ability, but he needed to apply himself consistently throughout matches.

“I saw some unbelievable shots against Murray, but doing that for a game or two isn’t going to win you a match,” Laver told BBC 5 Live.

He believed Kyrgios’ new mentor Lleyton Hewitt could hold the key to unlocking the enigmatic 20-year-old’s potential.

“Lleyton shows the class that he is and the consistency that he has in his own game,” Laver said.

“Trying to impart some of that into Nick’s game would be ideal.

“Nick is a great asset that Australia has if we can get him turned around into playing his best game.

“His best game can win a lot of matches and he can be a champion in his own right.”

Australian cricket great Shane Warne also weighed in on Thursday, urging the controversial Canberran not to waste his talent.

“You’re testing our patience mate, show us what you’re made of & how hungry you are to be the best in the world, it’s time to step up & start winning, no excuses,” Warne posted on Facebook.

“We all realise you’re only 20 and have a lot to learn buddy. But please don’t waste your talent, everyone in the world, especially us Australians want to respect u.”

Warne said the way people learn from mistakes was a demonstration of true character.

“No shame in losing, but show us you will never give up, that you will give it everything to be the best you can be,” Warne wrote.

“I believe in you & know you can do it, but now’s the time my friend.”