Deontay Wilder is reluctant to travel to the UK to face fellow heavyweight world champion Anthony Joshua.
A unification clash between the rivals to crown an undisputed champion is back on after the Brit beat Andy Ruiz Jr last weekend.
Wilder must first beat Tyson Fury in their rematch on February 22 while Joshua looks set to face back-to-back mandatory challengers in Kubrat Pulev and Oleksandr Usyk.
But if they can both cling on to their titles, a clash in 2021 may have to be held in the United States with Wilder's team raising concerns about the handling of Dillian Whyte's drug test before his fight with Oscar Rivas.
Whyte was cleared to fight - and then cleared of all charges - despite an abnormal reading in June.
And Wilder's coach Jay Deas told the Daily Mail : "Wherever [the fight] makes the most sense is fine with us. I don’t have any qualms about travelling or anything of that nature.
"But I will tell you: I would certainly be concerned given the Dillian Whyte situation.
"I know that they cleared him of the drug thing but still, when they had a positive result, and did not tell the opponent, that’s problematic. I think that’s potentially criminal. That’s a big, big issue for me.
"Also the fact that Dillian changed gloves without the other side being able to examine the gloves.
"So there would have to be a lot of things that we would have to talk about relative to the BBBoC and making sure that it was a level playing field because those things were horribly handled, and, in my opinion, set British boxing back quite a few years."
