Dillian Whyte’s promoter Eddie Hearn has urged fans to “wait for the facts” before judging the fighter.
The British heavyweight, 31, tested positive for a banned substance before Saturday’s win against Oscar Rivas.
If the result is confirmed, it would be Whyte’s second offence – he served a two-year suspension from 2012 to 2014 for unknowingly taking an illegal supplement – and he could face an eight-year ban.
“He is absolutely broken,” said Hearn.
Speaking to iFL TV, the promoter said Whyte was cleared to fight Colombian Rivas at London’s O2 Arena on Saturday after attending an independent panel hearing.
UK Anti-Doping (Ukad) told the BBC it would be making no comment. It is not known what the banned substance is.
The WBC said it has has not received any notification about a positive anti-doping test, adding that it is “reviewing the situation”.
“Before this bout this situation was dealt with,” Hearn added. “Dillian Whyte was cleared by that panel to take part in this fight.
“That is really important because people think this news came in and was brushed under the carpet and no-one knew about it. No. A process was adhered to. A hearing was had. He was confirmed and cleared to take part in this fight.”
Whyte, who is the mandatory challenger to American WBC world heavyweight champion Deontay Wilder, is expected to release a statement on Friday.
Hearn said: “Knowing what I know, I do not believe there is an issue with Dillian Whyte in this situation. Time will tell and that time should be able to give us the judgement.
“Give Dillian Whyte his time to address the situation, make his statement. Wait for the facts and make a judgement.”