Jannik Sinner: World number one ‘demolished’ by research, says coach Darren Cahill

Jannik Sinner is “physically and mentally” exhausted by the investigation into his positive test for a banned substance, says Darren Cahill, the coach of the world number one.

The Italian tested positive twice in March for clostebol, a steroid that can be used to build muscle mass, but was cleared of any wrongdoing or negligence by an independent court last week.

The International Tennis Integrity Agency (ITIA) found that Sinner was unintentionally infected with the substance by Giacomo Naldi, his physiotherapist.

Since Sinner was first notified of the doping violations in early April, he has won tournaments in Halle and Cincinnati and become world number one for the first time in his career.

“If you’re not a Jannik fan, you probably don’t see much difference from what he’s done the last few months because he’s still playing very well,” Cahill told ESPN colleague Chris McKendry.

“But if you are a fan of Jannik, you have seen a big change in his body language, his physicality on the pitch, his enthusiasm to be on the pitch. He has had a hard time and I think it has exhausted him physically and mentally.

“He got tonsillitis, which is why he missed the Olympics.

“I just want to emphasize that he is perhaps the most professional young man I have ever had the pleasure of working with. He would never intentionally do anything, and he is in a situation that is incredibly unfortunate.”

The World Anti-Doping Agency told BBC Sport it will “consider this decision carefully” before deciding whether to appeal, an approach the agency takes in all such cases.

Some players claim on social media that Sinner is treated differently because he is the world number one.

And 18-time Grand Slam singles champion Chris Evert says she believes authorities are protecting top players.

“They keep certain things secret when you’re a top player because they don’t want to get publicity, and the player doesn’t want to get publicity,” Evert said during a conference call ahead of ESPN’s coverage of the US Open.

“I think you get more protection there than if you were Joe Smith, number 400 in the world.”

Sinner’s lawyer denies that his client received special treatment.

“It’s completely fair to ask that question, but I think it’s actually the other way around,” Jamie Singer told BBC Radio 5 Live.

“Because he was such a superstar, the ITIA took it extremely seriously. But it was independent tribunals that made those decisions, and that’s the crucial point here – no one within the tennis world decided this, independent judges decided this.

“It’s had a huge impact on him. He’s become a different character this summer, he’s much more introverted.

“Jannik has never personally done anything wrong. This is a mistake by the physiotherapist, and so he lives with all this criticism because a physiotherapist made a mistake.”