Heavyweight champion Tyson Fury announced his retirement from boxing via social media on Monday, days after a reported failed drug test.
No official announcement has been made by Fury's management, who in the past has provided updates on the fighter's status.
Fury, 28, said he was hanging up his gloves with a profane message on Twitter, saying in part "Boxing is the saddest thing I ever took part in... I'm also retired....happy days.
Fury was reportedly notified that he failed a Voluntary Anti-Doping Association conducted test for cocaine on Sept. 22 and in danger of losing the WBO, IBF, and WBC titles he won after beating Wladimir Klitschko by unanimous decision on Nov.