The top court in global sport began hearing former Wimbledon and French Open champion Simona Halep’s appeal against a doping suspension that could end her career.

The 32-year-old Romanian arrived on Wednesday at the Court of Arbitration for Sport (CAS) in Lausanne for three-day proceedings that she hopes will see her provisional suspension lifted.

Halep has been provisionally suspended since October 2022 after testing positive for roxadustat, a banned drug that stimulates the production of red blood cells, at the U.S. Open that year.

Tennis anti-doping authorities also charged Halep with another doping offence last year due to irregularities in her athlete biological passport (ABP), a method designed to monitor different blood parameters over time to reveal potential doping.

Halep has vigorously denied the charges. The former world number one has blamed contaminated licensed supplements for her positive test at the U.S. Open.

She has accused the International Tennis Integrity Agency (ITIA) of charging her with an ABP violation after the group of experts who assessed her profile learned her identity.

An independent tribunal accepted Halep’s argument that she had taken a contaminated supplement but determined the volume she ingested could not have resulted in the concentration of roxadustat found in her positive sample.

Halep will not make any statement until the proceedings ends, CAS said. The court said it was unclear when a ruling might be made. Halep told Euronews in December that if the court dismisses her appeal, she could be compelled to retire.

“It’s catastrophic if it’s going to be four years,” she said. “I don’t know how I will handle it. Probably it will be the end of my career.”