Italy's Jannik Sinner plays a return to Australia's Christopher O'Connell during their men's singles third round match on day six of the US Open tennis tournament at the USTA Billie Jean King National Tennis Center in New York City, on August 31, 2024. Kena Betancur, AFP/File

MELBOURNE, Australia -- Jannik Sinner leaves Melbourne being talked about as a potential tennis great but first comes a hearing into his doping case at sport's highest court that could see him banned for up to two years.

The Italian swept past Alexander Zverev 6-3, 7-6 (7/4), 6-3 on Sunday in a clash of the top seeds to win back-to-back Australian Opens and shore up his status as the runaway world number one.

He also won the US Open last year, fast building a case for greatness.

READ: Clinical Sinner surges past Zverev to retain Australian Open title

But the 23-year-old's career has been dogged for the past nine months by a major doping scandal that should soon reach its conclusion.

He twice tested positive for traces of the steroid clostebol in March last year but was cleared by an independent tribunal of wrongdoing.

The World Anti-Doping Agency appealed to the Court of Arbitration for Sport (CAS) and is seeking a ban of up to two years.

The Italian, who denies knowingly doping, will have his hearing on April 16-17.

Sinner says that the drug entered his system when his physio used a spray containing it to treat a cut, then provided massage and sports therapy to the player.

Sinner, who is on a staggering 21-match win streak, said he was clear in himself that he was innocent but has admitted the case is never far from his mind.

One of his two coaches, Darren Cahill, said in Melbourne that "nobody's bulletproof" but that Sinner "deals with it as well as anybody that I've ever seen deal with pressure".

"I think to a large extent he finds playing tennis matches to be his safe place," Cahill added.

"That's where he can go and do his thing and feel like this is what he knows, this is what he understands, this is what he's good at.

"It's become a home for him to step on to the court and play tennis."

READ: Sinner in dark over verdict as ATP says doping case 'run by the book'

- Aiming for more -

The next Grand Slam of the year is the French Open, which starts in May, a month after the CAS hearing.

Sinner is the undoubted king of hard courts but he has yet to go beyond the semi-finals on the clay of Roland Garros or on the grass of Wimbledon.

"It's for sure one thing I always think about," Sinner said after his latest Australian Open triumph.

"You have to be a complete player, not only on one surface, but on also the other two.

"I believe last year was not a bad season at all on clay and also on grass. I can do better, yes, but let's see.

"On hard court I feel more comfortable. I think that we can see," he added after becoming the youngest man to go back-to-back at Melbourne Park since Jim Courier in 1993.

"But I take it as positive because on the other surfaces I still have to improve, I have to see how it works.

"I'm going to put a lot of energy in that, trying to find the right ways, and hopefully to go far also in the other Grand Slams that are not played on hard court."

- Another Djokovic? -

Sinner's other coach, Simone Vagnozzi, pointed out that Sinner still has plenty of time to stake his case for greatness given his age.

He is 14 years younger than 24-time Grand Slam champion Novak Djokovic, who is still playing.

Zverev called Sinner "prime Novak" after being well beaten in Sunday's final.

Now-retired fellow greats Roger Federer (20 Slams) and Rafael Nadal (22) also kept going until their mid to late 30s.

"He has already won three (major) tournaments. You never know what will happen in the future, but for sure he is the guy that tries to improve every day," said Vagnozzi.

"So I think he's one of the guys that can reach the top level. I mean, when we speak about the top level, we think about Novak, about Roger or Rafa.

"We are still a long way, but for sure (he) is one of the guys that can try to reach this kind of player."

© Agence France-Presse