ROME — Top-ranked tennis player Jannik Sinner said he was “very disappointed and also surprised” after a decision to clear him of wrongdoing following two positive drug tests was appealed by the World Anti-Doping Agency.

The Montreal-based body known as WADA announced Saturday that it is seeking a ban of one to two years for the U.S. Open champion but indicated that it does not plan to backdate an eventual suspension – which would mean that Sinner could keep his second Grand Slam title even if he is found guilty.

The appeal to the Switzerland-based Court of Arbitration for Sport (CAS) means that the case might not be resolved before Sinner begins defense of his Australian Open title in January. Sinner can continue playing while the appeal is being heard.

The announcement was made while Sinner was on court against Roman Safiullin at the China Open in Beijing.

“Obviously, I’m very disappointed and also surprised of this appeal, to be honest, because we had three hearings. All three hearings came out very positively for me,” the 23-year-old Sinner said after beating Safiullin.

“You know, I was not expecting it. I knew it couple of days ago, that they were going to appeal, that today it’s going to go official, so … it’s surprise,” the Italian added. “Maybe they just want to make sure that everything is in the right position.”

Sinner tested positive twice for an anabolic steroid in March but was not banned in a decision by an independent tribunal announced by the International Tennis Integrity Agency last month because the ITIA determined he was not to blame.

Sinner’s accepted explanation was that the banned performance-enhancer entered his system unintentionally through a massage from his physiotherapist, who had used a spray containing the steroid to treat his own cut finger.

WADA said it filed the appeal to CAS on Thursday.

“It is WADA’s view that the finding of ‘no fault or negligence’ was not correct under the applicable rules,” WADA said in a statement. “WADA is seeking a period of ineligibility of between one and two years. WADA is not seeking a disqualification of any results, save that which has already been imposed by the tribunal of first instance.”

WADA suggested the rules were not followed correctly despite prosecutor Nicolas Zbinden for tennis’ integrity body – which accepted Sinner’s version of events – being a lawyer who regularly works on high-profile cases for the global watchdog, including the successful appeal against Russian figure skater Kamila Valieva.

“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,” Sinner said later in a statement.

“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,” Sinner added.

An appeal verdict at CAS could come quickly – even within just a few months – if the parties agree to cooperate. At least that’s how it worked in another high-profile doping case in tennis involving Maria Sharapova.

Sharapova tested positive at the Australian Open in January 2016 for the newly banned heart medication meldonium. She was banned for two years in June that year by the International Tennis Federation.

The Russian star appealed to CAS, had an appeal hearing in New York before three judges that September and four weeks later got the verdict that cut her ban to 15 months.

The entire process for Sharapova with CAS took just four months – far shorter than most doping cases, which typically last for about one year. The timeline can stall with the complexities of picking a judging panel, finding a hearing date and parties exchanging documents and evidence from expert witnesses.

During the Indian Wells, California, hard-court event in March, Sinner tested positive for low levels of a metabolite of Clostebol, a banned anabolic steroid that can be used for ophthalmological and dermatological use. It’s the same drug for which San Diego Padres star Fernando Tatis Jr. was suspended by Major League Baseball in 2022.

Sinner tested positive again eight days later in an out-of-competition sample.

He was provisionally suspended twice by the tennis integrity body because of those test results, but he successfully appealed twice to an independent tribunal judge and was allowed to keep competing on tour.

Sinner said his test results happened because his fitness trainer purchased an over-the-counter spray called Trofodermin in Italy that contained Clostebol and gave it to Sinner’s physiotherapist to treat a cut on the physiotherapist’s finger. The physiotherapist then treated Sinner without wearing gloves.

Sinner said the amount of banned substance he tested for ammounted to “.000000001.”

The ITIA said it accepted Sinner’s explanation, after 10 interviews with the player and his entourage, and the independent panel agreed at a hearing on Aug. 15.

The tennis integrity body decision did order to Sinner to lose the $325,000 in prize money and 400 rankings points he earned at the tournament in Indian Wells.

Sinner later announced that he had fired his two trainers.

“We have a lot of confidence in (CAS), which should have the final word in the case,” said Angelo Binaghi, president of the Italian tennis and padel federation. “I’m sure that the only effect of the WADA appeal will be positive. Because it will formalize his innocence.”

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AP Sports Writer Graham Dunbar in Lausanne, Switzerland, contributed to this report.