American professional boxer Jarrell Miller has recorded an “adverse finding” in a dope test ahead of his world title unification fight with Anthony Joshua.
The former kickboxer is due to fight IBF, WBA, and WBO champion Joshua on June 1 at Madison Square Garden in New York.
But the American, who has repeatedly accused Joshua of cheating, could now face a ban after testing positive for a banned substance.
Joshua’s promoter Eddie Hearn said: “We have been informed by VADA that there has been an adverse finding in Jarrell Miller’s sample collected on March 20.
“We are working with all relevant parties and will update with more details soon. AJ’s preparation continues for June 1 at MSG.”
Miller tested positive for GW1516, a substance which increases aerobic power and endurance.
It was added to the World Anti-Doping Agency’s banned list in 2009 and reportedly costs up to $1000 for 10g on the black market.
Joshua is still expected to fight on June 1 with Hearn scrambling to find an opponent.
The Brit was originally expected to fight Dillian Whyte at Wembley this month but a deal could not be reached.
He also failed to agree terms with fellow world champion Deontay Wilder who takes on Dominic Breazeale on May 18.