Oleksandr Usyk and Tyson Fury until April 1 to agree to a heavyweight unification bout, the World Boxing Association (WBA) has said.
The pair are seeking to come to terms on a fight that would crown the first undisputed heavyweight champion since Lennox Lewis.
Though discussions have appeared close to producing a resolution on several occasions, changes in demands from both camps have prolonged the process.
With time running out to meet the provisional April 29 fight date pencilled in for Wembley Stadium, the WBA has now issued a final deadline.
"March 10 was the deadline for the initial negotiations granted by the WBA," a WBA statement read.
"After the WBA announced the situation, Usyk and Fury’s teams contacted each other to inform that the pact was on its way and that the fight was going to take place.
Usyk v. Fury update: @WBABoxing deadline to receive signed bout contracts is April 1st. Otherwise the Dobouis mandatory negotiations will be ordered.— Gilberto J Mendoza (@GilberticoWBA) March 19, 2023
"Now, the WBA has given them this new deadline that expires on April 1 and hopes that the fight can take place, since it is what the fans are asking for and what the whole boxing world is waiting for."
The WBA has held off on issuing Usyk with a mandatory fight against Daniel Dubois. Usyk holds the 'super' champion belt while Dubois is the 'regular' champion.
Usyk and Fury's potential fight has dominated the sport across the first few months of 2023, with the pair trading barbs as they seek to hammer out a deal.
The Ukrainian last fought in August, when he defended his titles against Anthony Joshua in their rematch, while Briton Fury completed his trilogy with Derek Chisora in December, winning with a 10th-round knockout.