Tyson Fury's boxing career could be over after the reigning IBF, WBO and WBA heavyweight champion announced his retirement in a profanity-filled tweet.

The post came almost two weeks after Fury called off his world heavyweight title rematch against Wladimir Klitschko for a second time.

The official reason given then was that Fury was "medically unfit." The British fighter had earlier been charged by the U.K. Anti-Doping agency over a positive test.

Fury, who didn't deny fresh reports last week about drug use, tweeted Monday: "Boxing is the saddest thing I ever took part in, all a pile of (expletive), I'm the greatest, & I'm also retired." The post ended with another obscenity.

Fury beat Klitschko in Germany in November 2015 to claim the WBA, WBO and IBF titles.


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