Maria Sharapova has lodged an appeal to the Court of Arbitration for Sport (CAS) to challenge a two-year suspension which was imposed on her last week.
The five-time grand-slam champion was provisionally banned by the International Tennis Federation (ITF) in March after testing positive for banned substance meldonium at this year's Australian Open.
Former world number one Sharapova claimed to be unaware that meldonium had been added to WADA's prohibited list at the start of 2016.
The ITF announced last Wednesday that an independent tribunal had handed out a two-year suspension on the Russian, backdated to January 26, 2016 - the date of her positive test in Melbourne.
Sharapova reacted by vowing to appeal against what the 29-year-old considers to be an "unfairly harsh" ban and it was confirmed on Tuesday that she has taken her case to CAS.