Five-time grand slam champion Maria Sharapova was Wednesday banned from tennis for two years after testing positive for a newly banned substance.
The International Tennis Federation said in a statement that it had "imposed a period of ineligibility of two years, commencing on 26 January 2016," the day of her test.
Sharapova immediately said she will appeal the potentially career-ending sanction.
"I intend to stand for what I believe is right and that's why I will fight to be back on the tennis court as soon as possible," she wrote in a statement on her Facebook site.
The infraction occurred at the Australian Open, with the 29-year-old testing positive for meldonium, a heart medication which had been declared illegal a few weeks earlier by anti-doping chiefs.
The ITF provisionally banned the Russian in March after she came out with an announcement of her positive January test.
Sharapova said she had been prescribed meldonium for a decade by her personal physician.
Anti-doping officials have confessed that there is no scientific evidence yet as to how long it takes the newly illegal substance to leave the body. The medicine was declared illegal from the start of January.
The former highest-earning woman in all of sport, reportedly produced very low levels of the substance.
Sharapova said in March that she was unaware of email and other electronic communications from the ITF which warned that meldonium would become illegal from January 1.
"The ITF accepts that she did not know that Mildronate [meldonium's trade name] contained a Prohibited Substance but argues that in taking the medication she knowingly and manifestly disregarded the risk of contravening the anti-doping rules, and thus committed an intentional violation," the ITF said in an explanatory statement.
It added that the player had admitted to "some fault" but that she placed blame on the organization for not taking "reasonable steps to publicise the change" to its doping rules.