Maria Sharapova has been suspended for two years by the International Tennis Federation for testing positive for meldonium at the Australian Open.
The decision, announced on Wednesday, can be appealed to the Court of Arbitration for Sport.
The five-time Grand Slam champion was provisionally suspended by the ITF in early March, when she announced at a news conference in Los Angeles that she failed a doping test in January.
Sharapova said then she was not aware that the World Anti-Doping Agency had barred athletes from using meldonium, also known as mildronate, as of Jan. 1.
Her lawyer, John Haggerty, says Sharapova took the substance after that date.
Sharapova said she first was prescribed the Latvian-made drug, typically used for heart conditions, for medical reasons in 2006.
The Russian star has however promised to appeal the suspension.
Sharapova said: "I cannot accept an unfairly harsh two-year suspension."