Star boxer Ryan Garcia tested positive for the performance-enhancing substance Ostarine the day before and the day of his upset win over Devin Haney last month, per a Voluntary Anti-Doping Association letter obtained by ESPN on Wednesday.
The tests were taken prior to the fight, but the results weren't known until later.
Garcia has 10 days to request that his B-sample be tested. Garcia's A-sample also screened positive for 19-norandrosterone but its presence is unconfirmed at this time.
Garcia, 25, floored Haney three times during the majority-decision victory, but that result now stands to be overturned unless the B-sample returns negative, which is rare.