Tyson Fury looks set to lose one of his heavyweight world titles just days after defeating Wladimir Klitschko to claim the WBA, WBO and IBF belts.
A rematch clause negotiated into the contract for the fight has been activated by Klitschko, who lost for the first time in 11 years in a surprise defeat to Fury on Saturday.
Yet the International Boxing Federation (IBF) say they will strip Fury of their belt should he take on the Ukrainian before facing their mandatory challenger Vyacheslav Glazkov.
"To be clear, Tyson Fury must fight Vyacheslav Glazkov next", IBF chairman Lindsey Tucker told World Boxing News. "Regarding the Klitschko rematch taking precedence, it's just the opposite as the mandatory takes priority of the rematch."
The IBF's rules specifically outlaw rematch clauses being written into contracts for title fights.
Rule 3B states:
No contract for a Championship contest shall contain any clause or provision, whatsoever, guaranteeing or in any way assuring or promising either contestant a return Championship contest where such clause or provision interferes with the mandatory defence of the title.
However, Fury's promoter Mick Hennessy claims the unbeaten fighter would rather bin the IBF belt than take on unbeaten Ukrainian heavyweight Glazkov in his next match.
Hennessy said: "If they want to hustle and bully Tyson into fighting Glazkov, Tyson will end up putting the belt in the bin at a major press conference.
"If they force Tyson to fight Glazkov, it will not happen. Glazkov means nothing, he has zero value...Glazkov will not get in the way of a rematch with Klitschko...The rematch clause takes precedence over everything else and that's the biggest fight in the division."
A date or venue for a Fury v Klitschko rematch has not yet been decided, but his uncle and trainer Peter Fury says his team are eyeing Wembley as a potential location.