Jannik Sinner says he is 'disappointed' after the world anti-doping agency (WADA) appealed against the decision to clear the Italian tennis star of doping. The world No. 1 was exonerated by an independent tribunal which ruled that he was not to blame for two positive tests.

Sinner tested positive for the banned anabolic steroid clostebol in March. However, he was able to argue that he had no knowledge of the contamination, which he successfully claimed was caused by his physio using a spray on his own cut before giving the US Open champion a massage.

WADA announced today (Saturday) that they have appealed against that ruling to the Court of Arbitration for Sport (CAS). Sinner has questioned the decision but insists he will fully cooperate with the appeal process.

“I am disappointed to hear that WADA have chosen to appeal the result of my ITIA hearing after the independent judges had exonerated me and deemed me to be innocent," the 22-year-old said.

“Over the past few months and throughout this process there have been three separate hearings in each case confirming my innocence.

“Several months of interviews and investigations culminated in three senior judges scrutinising every detail through a formal hearing. They issued an in-depth judgement explaining why they determined me not at fault, with clear evidence provided and my cooperation throughout.

“On the back of such a robust process both the ITIA and the Italian anti-doping authority accepted it and waived their right to appeal.

“I understand these things need to be thoroughly investigated to maintain the integrity of the sport we all love. However, it is difficult to see what will be gained by asking a different set of three judges to look at the same facts and documentation all over again.

“This being said, I have nothing to hide, and as I have done throughout the summer, I will cooperate fully with the appeal process and provide whatever may be needed to prove my innocence once again.

“As the case is now pending before CAS, I won’t comment further.”

The initial decision to clear Sinner came in the days before the US Open. He went on to win the tournament, claiming his second Grand Slam title following his Australian Open triumph earlier this year.

Sinner is currently competing at the China Open. He progressed to the quarter-final after beating Roman Saffiullin 3-6 6-2 6-3.