Eddie Hearn, promoter for heavyweight Anthony Joshua, does not expect the fight with Deontay Wilder to happen until the month of January.
The fight had initially been targeted to take place on a December date in Saudi Arabia.
Hearn is also casting doubt that an undisputed showdown between Tyson Fury and Oleksandr Usyk will take place on the same card.
Because Fury is now scheduled to face former UFC champion Francis Ngannou on October 28 in Saudi Arabia,, there likely won't be enough time to negotiate a fight with Uysk for December or January.
Skills Challenge Entertainment [SEC], a Saudi promotional company, is bankrolling the heavyweight plans.
"I think it will be January [Joshua vs Wilder], I'm not sure whether Fury vs Usyk gets made [on the same card]," Hearn told Boxing Social.
"I don't expect the Ngannou fight will be so taxing that he can't fight in January. But at the same time he would have done a training camp and also you don't know if he wants the fight, which lots of people suggest he doesn't."
SEC is very concerned with Joshua's upcoming fight, which is a high-stakes rematch against Dillian Whyte on August 12 at the O2 Arena in Las Vegas.
Hearn admits that a Joshua-Wilder showdown is without question dependent on Joshua winning his upcoming return.
"The finalization of the Wilder fight is on hold until they [SEC] see what happens on August 12 and that's the risk that we're in. It's a big risk [with Joshua facing Whyte], is it the right risk? We'll find out, AJ wanted a real fight, he wasn't motivated to take a lesser, smaller fight, but the Wilder fight will be dependent on victory at the O2 Arena on August 12," Hearn said.