Tyson Fury has called fellow heavyweight champion Oleksandr Usyk a “14-stone coward” in an expletive-laden social media post after talks for an undisputed fight broke down.
A proposed bout at Wembley Stadium on 29 April fell through this week.
Usyk had agreed a 70/30 purse split in Fury’s favour with terms for a rematch the only outstanding issue.
“Tried all week to get out of it, begging for a rematch,” Fury said in an Instagram story on Thursday.
In a 50-second clip, which included numerous insults targeted at Usyk, Fury added: “You got your rematch and didn’t want to fight at that. You were never man enough to tangle with the Gypsy King ever in your life.”
Fury currently holds the WBC heavyweight belt, while Ukraine’s Usyk – who beat Britain’s Anthony Joshua for a second time last year – has the others in the division.
After months of negotiations, Fury’s promoter, Frank Warren, said on Wednesday the fight is definitely off and “does not think” it will happen in the future.
Usyk, the WBA (Super), IBF, WBO and Ring magazine champion, wants a proposed rematch to happen in November or December, but there are fears among Team Fury that the four belts would have fractured by then.
If the Ukrainian overcame Fury in their first fight, he would also expect an improved purse split in a rematch.
Both parties have until 1 April to agree a deal after the WBA said it will wait until that date before ordering Usyk to fight mandatory challenger Daniel Dubois.
“Keep running,” Fury continued. “Fight Dubois at the Copper Box now.”
Londoner Dubois, meanwhile, has said he “definitely, 100%” wants a world-title shot next.
He told Pitch Boxing: “Why not go for the big one now? I’m 100% going for it and I believe I can knock him [Usyk] out.”
There has not been an undisputed heavyweight champion since 1999 when Lennox Lewis beat Evander Holyfield – and there has never been one in the four-belt era.