Anthony Joshua will fight with Andy Ruiz Jr on June 1 in New York.
The WBA, WBO and IBF heavyweight champion was due to face off against Jarrell Miller before the American failed three drugs test.
The American tested positive for GW1516 (a metabolic modulator is also known as cardarine and endurobol) in a VADA test taken March 20.
Miller has been given a six-month ‘ban’ by the WBA, however, it doesn’t actually prevent the heavyweight from fighting, as they do not have that power.
Ruiz Jr is the huge underdog for the bout at Madison Square Garden but he has lost just one of his 33 fights.