The International Boxing Federation has insisted that Tyson Fury must face mandatory challenger Vyacheslav Glazkov in his next fight in order to keep hold of his title.
The IBF belt was one of three heavyweight titles claimed by the Briton when he defeated Wladimir Klitschko last weekend, also earning the WBA and WBO crowns.
It is expected that Klitschko and Fury will have a rematch, but IBF chairman Lindsey Tucker told World Boxing News: "To be clear, Tyson Fury must fight Vyacheslav Glazkov next. If they agree terms before December 11 we cancel the purse bid. If it goes to a purse bid, the winning bidder has 90 days to do the fight. Regarding the Klitschko rematch taking precedence, it's just the opposite as the mandatory takes priority of the rematch."
WBC champion Deontay Wilder has also expressed interest in a unification bout.