Olympic champion swimmer Sun Yang has submitted an appeal over his eight-year doping ban to Switzerland's highest court.
An official at the Swiss Federal Tribunal confirmed to the PA news agency that the Chinese athlete had submitted an appeal ahead of the deadline.
The supreme court is the designated appeal body for decisions made in the Court of Arbitration for Sport (CAS).
Sun was handed the lengthy suspension in February after the World Anti-Doping Agency challenged a controversial decision by swimming's governing body FINA to clear him of a doping offence.
The Olympic 200-metre freestyle champion was accused of smashing the vials containing his blood after a row with a team of FINA drug-testers at his home in September 2018.
The 28-year-old, his mother and entourage allegedly interfered with the FINA team's efforts to get samples because they did not believe the testers were properly accredited or qualified but a CAS panel unanimously found him in breach of doping regulations.
Sun, who had already served a three-month ban for an earlier offence, clashed angrily with Britain's Duncan Scott during his gold medal ceremony at the World Aquatics Championships in July 2019 after the Scot refused to shake his hand. Sun branded Scott, who finished third, a "loser".
The CAS website states that judicial recourse to the Swiss Federal Tribunal is allowed on a "very limited number of grounds", such as lack of jurisdiction, violation of the right to a fair hearing or incompatibility with public policy.
