WBC heavyweight champion Tyson Fury says fellow Briton Anthony Joshua “does not want to fight” him for the world title later this year.
Joshua’s team said they have “accepted all terms” to the offer.
But Fury said: “I will be fighting on 3 December if [Joshua] does not sign this contract, which I don’t think he will.”
He added: “You’ve had the contract for I don’t know how long and ain’t signing it. You do not want to fight.”
In the same social media post, Fury used an expletive to describe Ukraine’s Usyk, who called for a unification fight with Fury after winning his rematch with Joshua.
Fury’s promoter Frank Warren then said the match “will be made” and Usyk, 35, said in an interview posted on his YouTube page on Thursday that he wants it to be one of his last three fights before retiring.
“The unification of all the belts is much more important than just a fight or another defence,” he said.
“I want to outbox Fury and I don’t want to work that much just for another defence. There’s much more than that and I can achieve it.”
Usyk also wants a lucrative “freak” fight with super-middleweight champion Saul ‘Canelo’ Alvarez before ending his career at Kyiv’s Olimpiyskiy Stadium.
Alvarez claimed a dominant points win over Gennady Golovkin last weekend to settle their trilogy with a second win for the Mexican, 32, after a controversial draw in his first bout with the Kazakh.
“I can have three more fights at the very most,” Usyk added.
“It is the most realistic to be in my top form. With Fury, Canelo and a farewell fight at Olimpiyskiy.
“With Canelo he said that he wanted to fight me. It would be a freak fight just for the sake of earning money.”