In early October, world number nine Simona Halep was caught in a doping test.
Now the B sample has also been analyzed, which showed samples of the substance roxadustat.
Halep - formerly number one in the world - is now suspended.
"It came as the biggest shock of my life," writes Halep on Instagram.
"Confused and let down"
The 31-year-old continues:
“Throughout my career, the idea of cheating has never crossed my mind because it goes against everything I stand for.
To end up in such an unfair situation, makes me feel confused and let down".
She will fight to prove her innocence.
"I will fight to the end and prove that I have never taken a banned substance and I believe that the truth will come out sooner or later".