Anthony Joshua’s US debut has been plunged into uncertainty following the revelation that scheduled opponent Jarrell Miller has tested positive for the banned substance GW1516.

Joshua’s promotor Eddie Hearn broke the news on Twitter on Wednesday before ESPN’s Dan Rafael followed up the claims with a detailed report on Miller’s positive result.

As yet, the fight remains on, and Hearn has confirmed that Joshua will fight at Madison Square Garden in New York on June 1, whether the opponent is Miller or not, though the American will hope his B sample returns negative should he, as expected, request it to be tested.

With Miller now likely to face a hearing, previous form suggests the New York State Athletic Commission will refuse to license him for the fight if the B sample shows the same result, meaning Hearn is already lining up potential alternative opponents for Joshua.

According to the Daily Mail, 29-year-old Joshua – the IBF, WBA Super and WBO heavyweight champion – could defend his belts against one of five short-listed replacements, namely Luis Ortiz, Adam Kownacki, Kubrat Pulev, Michael Hunter or Manuel Charr.

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Ortiz Could Be Avoided

Ortiz, ranked third with the WBC, would be the most appealing opponent from a neutral’s point of view, but from Joshua’s camp the southpaw would appear the most dangerous option.

Boxing bookmakers reflect that view, making Ortiz just 4/1 (+400) to beat Joshua should they fight before June 2, the shortest price on offer of all AJ’s potential opponents. Joshua would go off as the 1/7 (-700) favourite should they fight.

Given Hearn’s reluctance to risk Joshua’s undefeated record, a more likely opponent appears to be Polish-born New Yorker Kownacki, who is the biggest outsider of the mooted replacements at 8/1 (+800).

Joseph Parker, meanwhile, did not waste any time in throwing his hat into the ring, tweeting that he was ‘ready and willing’ to step in for a re-match.

Parker is the only fighter to have taken Joshua the distance having suffered a Unanimous Decision loss in Principality Stadium in Cardiff almost a year ago.

He has since been knocked out by Dillian Whyte so his stock is low, and bookies don’t fancy his chances second time around either, offering 7/1 (+700) on the New Zealander should he step in to fight AJ again.

Meanwhile, Miller’s promoter Dmitriy Salita has not given up hope on his fighter getting his big payday against Joshua.

“We are in the process of obtaining further information about Vada's finding and will have more to say soon on this developing situation,” he said.

“In the meantime Jarrell continues to train for his June 1 fight against Anthony Joshua.”