Just hours before the deadline, Dillian Whyte signed a deal to face fellow Brit and undefeated heavyweight champion Tyson Fury.
Whyte, 33, had until 6am GMT on Tuesday to put pen to paper but had spent to last few days looking into the finer details on the contract.
They are now expected to have a press conference in London later this week and could announce the date and venue of the blockbuster clash.
April 23 is the date and Wembley Stadium is poised to host the fight although Cardiff's Principality Stadium is also an option.
Frank Warren's Queensberry Promotions will promote the bout and it is live and exclusive to BT Sport Box Office in the UK.
The legendary promoter won the purse bids with a $41m bid - and it will see ESPN+ broadcast the event across the Atlantic.
The Gypsy King was left unimpressed with the delay of Whyte's signature and branded him a 'sausage'.
Fury said: "I just heard that little sausage Dillian Whyte wants paying to turn up for a press conference. You little silly fat sausage, you're getting that [a fist], you coward.
"Hi guys, just a quick one. I'm setting up a Just Giving page for Dillian Whyte so he can show up to the press conference and I'm going to donate first. My donation is 47p, you useless dosser."