Simona Halep, a two-time Grand Slam champion, has been given a temporary ban from tennis after testing positive for an illegal substance.
At the US Open in August, the former world number one gave a sample that tested positively for roxadustat.
The anti-anemia medication roxadustat encourages the body to produce more red blood cells.
The ninth-ranked player in the world, Romanian Halep, described the favourable outcome as the "greatest shock of her life."
“Today begins the hardest match of my life: a fight for the truth,” the 31-year-old wrote on Twitter.
“Throughout my whole career, the idea of cheating never even crossed my mind once, as it is totally against all the values I have been educated with.
“Facing such an unfair situation, I feel completely confused and betrayed.”
Halep, who won the French Open in 2018 and Wimbledon the following year, said that she had tested positive for roxadustat “in an extremely low quantity”, adding she would “fight until the end”.
She is the highest-profile tennis player to fail a drugs test since Maria Sharapova in 2016.
“It’s not about titles or the money,” said Halep. “It’s about honour, and the love story I have developed with the game of tennis over the last 25 years.”
In September, Halep announced she had undergone nose surgery to improve her breathing and was ending her 2022 season early.