Anthony Joshua insists he will sign the contract to fight Tyson Fury after the WBC champion issued an ultimatum if they are to put together their all-British heavyweight battle this year.
Fury, who initially called for Joshua to sign the contract by Monday, returned to Instagram to state that Joshua had until 5pm otherwise he will walk away from the deal.
"Today is D-Day people. Are you going to sign the contract you big p**** or are you not going to sign it?" said Fury.
"When Wilder sent me the contract for Wilder 1 I signed it within 24 hours because I wanted to smash his face in.
"You've had the contract for 10 days now, b****, and still haven't signed it. If it's not done by 5pm today GK (Gypsy King) is moving on."
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The relevant TV broadcasters are meeting on Monday. That will be a key point in discussions.
Joshua took to social media to say: "It's not in my hands, it's with the legal team. That's why you hire lawyers. You know the history of boxing, make sure you get your legal terms right.
"Of course, I'm going to sign a contract. It's just with some lawyers at the minute."
Joshua's representatives have received a contract and talks between the rival promoters are by all accounts amicable. But time is of the essence if a major fight is to be made by early December.
"I was optimistic about three weeks ago but it shouldn't be taking this long to sign a contact," Fury previously said.
"I'm not waiting around for some guy who's lost three of his last five fights. He's lucky that I'm giving him a world title shot. If not he'll have to wait a long time to get another one.
"I don't mind chucking him a bone. But I don't want him to start dictating [stuff] to me. He is an invited guest at my party. My rules. So if you want to play the game, come to the banquet and take your seat. If not, go to your own banquet."
"Sign the contract," he said in a direct challenge to Joshua. "I'm going to smash your face in."
Fury will fight before the end of the year, but the undisputed showdown with WBO, WBA and IBF titlist Oleksandr Usyk will have to wait until next year.
"We offered him [Usyk] the December 17 date in Saudi Arabia for the undisputed heavyweight championship of the world," Fury said.
"Everybody wanted that day and Usyk said he was injured and he couldn't do it till next year. And now he's saying I'm scared of him!"
He added: "I'll put this fist right through his face."
Fury concluded: "I'm trying to get an opponent for December 3 and if AJ fights then I'll eat hay with the donkeys and if he doesn't then I'll fight somebody else.
"They're all running scared. I'll fight anybody, any time, any place."