Heavyweight contender Jarrell "Big Baby" Miller tested positive for the banned substance GW1516 before his scheduled challenge from unified world titleholder Anthony Joshua, three sources with knowledge of the results told ESPN on Tuesday night.
The fight will be held on June 1 at Madison Square Garden in New York and will serve as Joshua's American debut.
The results of the tests, which came to light on Tuesday, were from a urine test conducted by the voluntary anti-doping badociation conducted by Miller on March 20.
Ironically, Miller accused Joshua of using PED during his press tour to announce the fight.
Eddie Hearn, Joshua's promoter, wrote in a tweet on Tuesday evening: "VADA informed us that there was an adverse finding in the Jarrell Miller sample collected on March 20, 2019. We are working with all relevant parties and will update with more information, details soon, AJ's preparation continues on June 1 at MSG. "