Maria Sharapova, the five-time tennis Grand Slam winner, will face an anti-doping panel in London on Wednesday after taking the banned drug meldonium.
The 29-year-old Russian failed a doping test at the Australian Open in January.
Meldonium, a heart disease drug, was added to the World Anti-Doping Agency’s banned list on 1 January.
The International Tennis Federation panel could issue a four-year-ban, but experts say a six-month or 12-month punishment is more likely.
That is because Wada admitted in April that scientists were unsure how long meldonium stayed in the system.
It even suggested athletes who tested positive for the substance before 1 March could avoid bans, provided they had stopped taking it before 1 January.