Nick Kyrgios has been branded 'overrated' and a 'clown' by two former tennis heavyweights.

The Australian's loud personality and brash antics on court have made him a marmite figure since turning professional 11 years ago. He has mainly been seen in punditry roles over the past two years, with knee and wrist problems derailing his career long before his 30th birthday.

But Kyrgios has pledged to give Grand Slam glory another shot at the Australian Open in January, where he reached the quarter-finals in 2015 and won the men's doubles title alongside Thanasi Kokkinakis seven years later.

Not everyone is excited about Kyrgios' comeback. Former Tour Finals winner and world No 3 Nikolay Davydenko has never been particularly impressed by the 29-year-old, and the Russian claims not to be invested in his return to action.

"He is generally overrated," Davydenko told BetBoom Tennis. "When it was time to play, he was always injured. In short, let’s forget about him."

His compatriot, Elana Vesnina, was similarly cutting in her assessment of Kyrgios. Though the three-time Grand Slam doubles champion did at least afford him a small amount of credit.

"Clown, I agree," she said. "But he was incredibly talented and gifted. He had a powerful serve and a superb forehand. But when it came to winning a major title, all that went up in smoke."

The pair's criticism highlights exactly why Kyrgios has chosen to return to the court after so long on the sidelines. The Canberra-born competitor is widely viewed as one of the most naturally talented players of his generation, but he does not yet have the trophy cabinet to match.

"I am coming back because something is keeping me around the game," he told the Code Sports podcast. "I have beaten pretty much every person that has been put in front of me, made the final of a Grand Slam, won a doubles title in a Grand Slam, won multiple titles and made money.

"But I think the one thing that is now my target is a Grand Slam. I think that will be the only thing that will shut people up at the end of the day."

Reflecting on a tough couple of years, he added: "I just miss being out there playing in front of a home crowd. The [wrist] injury I had was brutal. The surgeon said I probably wouldn’t be able to play again.

"But I said, 'Whatever, just try and get me another two to three years of my career'. I just want to be out there, lighting up the crowd and playing in front of my own country."