Tyson Fury and Deontay Wilder are set to push back their trilogy installment to October 9, according to sources.
At the start of the year the "Gypsy King" was in talks to secure a historic showdown against Anthony Joshua for all four major world titles at heavyweight.
However, a court ruling blocked the fight and Daniel Weinstein ordered a rematch between Fury and Wilder.
Weinstein ruled that Fury must face Wilder before September 15 and the pair had originally agreed on July 24 as the date in Las Vegas.
Because of Fury testing positive to Covid-19, alongside up to nine other members from his camp, there will need to be an appeal to extend the deadline.
Neither fighter has been in the ring since their February 2020 bout, which Fury won via TKO in round seven.
Shelly Finkel - co-manager of Wilder - criticised Fury for the collapse of the summer showdown.
"If Fury and his team had taken their vaccinations then there would have been a fight on July 24," Finkel exclusively told Planet Sport.
"All we want is to reschedule and get him in the ring," he added.
Does this delay Joshua vs Fury?
No. Joshua has WBO mandatory challenger Oleksandr Usyk to deal with first and it is expected to happen towards the end of September. Tottenham Hotspur Stadium is set to host the heavyweight event.
While Eddie Hearn had spoken about making Joshua-Fury in December, it was wishful thinking.
With both fights set to happen in September and October, expect any chance of a historic unification to take place in April or May - that is if both win their respective bouts.
There is no chance of Dillian Whyte being drafted in to fight Wilder on July 24 for multiple reasons.
Can British fans attend the Las Vegas spectacle?
The news comes as a blow to fans eagerly awaiting Joshua-Fury but there is some potential good news about the postponement.
With vaccinations being rolled out, there is a good chance that borders will reopen and if so, British fans will be able to travel and attend Fury-Wilder.
The fight will still take place at the T-Mobile Arena - a venue which holds just under 21,000.
It will also be a welcome addition to Top Rank's Bob Arum and everyone involved in the fight with it adding some much needed revenue to the trilogy.