South Africa wing Aphiwe Dyantyi, who won world rugby's breakthrough player award in 2018, says he has failed a doping test.
Dyantyi says in a statement he tested positive for a banned substance at a Springboks training camp in July.
He denies taking "any prohibited substance, intentionally or negligently, to enhance my performance on the field" and has requested his 'B' sample be tested. The substance wasn't named.
Dyantyi, who turns 25 tomorrow, has scored six tries in 13 Tests, including two in the 36-34 victory over the All Blacks in New Zealand last year.
He last played a test in November and has been limited by injury this season. He wasn't expected to be included in the Springboks' Rugby World Cup squad, which will be named tomorrow.