Unified champion Oleksandr Usyk is set to walk away from talks with Tyson Fury over an undisputed heavyweight fight.
The bout was pencilled in for 29 April at Wembley Stadium and Usyk had agreed to a 70/30 split in Fury's favour.
But the terms for an immediate rematch have proved a sticking point during negotiations.
WBC champion Fury, 34, was against a rematch clause, while Team Usyk insist they did everything within their power to make the fight happen.
Over the weekend Team Fury had thought the deal was done and were even making preparations for an official statement.
Fury's co-promoter Frank Warren teased on Twitter on Sunday that news was imminent, but Monday saw the two sides again clash over the prospect of a rematch.
Usyk, 36, who is the WBA (Super), IBF, WBO and Ring magazine champion, wants a rematch clause just as Briton Anthony Joshua did when they fought in 2021.
Joshua was given the chance to immediately regain the titles in Saudi Arabia and Usyk would want the same opportunity if he was beaten.
Team Fury feel a rematch is unnecessary, believing the heavyweight titles could fracture once the undisputed fight has happened.
A rematch clause for both fighters, however, was initially agreed over the weekend but talks stalled again over the potential purse split.
There has not been an undisputed heavyweight champion since 1999 when Lennox Lewis beat Evander Holyfield - and never been one in the four-belt era.
It is expensive to pay sanctioning fees to four separate bodies and there has been an expectation an undisputed champion could immediately vacate at least one of the titles.
The WBA will now look to order Usyk to defend his belt against mandatory challenger Daniel Dubois.
The 25-year-old Briton and the WBA were prepared to allow the undisputed fight to happen, but Dubois, who is also promoted by Warren, will now push to face Ukrainian Usyk next.