Jannik Sinner isn’t in the clear just yet.

The World Anti-Doping Agency (WADA) has appealed to the Court of Arbitration for Sport (CAS) over a decision in August to clear the No. 1 ranked men’s tennis player in the world — and U.S. Open winner earlier this month — of wrongdoing for failed drug tests.

Sinner, 23, twice tested positive twice for Clostebol — a banned anabolic steroid — in March.

He was not suspended, however — the International Tennis Integrity Agency (ITIA) announced an independent tribunal’s decision in August that Sinner was not to blame.

WADA made its announcement to appeal the decision while the Italian was on the court at the China Open in Beijing, beating Roman Safiullin in the Round of 16.

“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,” Sinner said after the match. “You know, I was not expecting it.

“We always talk about the same thing. Maybe they just want to make sure that everything is in the right position. Yeah, I’m just surprised that they appealed.”

WADA is seeking a ban of one to two years.

It does not plan to back-date a potential ban, however, meaning Sinner would keep his U.S Open title, which marked his second Grand Slam win, if he is found guilty.

Sinner claimed that Clostebol entered his body unintentionally through a massage from his physiotherapist, who had used a spray containing the steroid to treat his own cut finger.

The independent tribunal accepted that explanation, but WADA does not.

“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.”