Anthony Joshua has been offered a guaranteed purse of 50million US dollars (£35.9m) by Deontay Wilder's team in order to arrange a much-anticipated world heavyweight unification title showdown.
Joshua has been given 24 hours to sign the contract, labelled "a wonderful PR move" by his promoter Eddie Hearn, and the Watford fighter wasted little time in responding to his rival, saying: "Let's roll".
The pair hold all four major world titles between them and speculation of a bout has intensified since Joshua defeated Joseph Parker last month to unify the WBA, IBF and WBO titles.
WBC champion Deontay Wilder was offered a flat fee of 12.5million US dollars by Hearn recently but the American's handlers have made a counter proposal.
Wilder hinted he was ready to give in to Joshua's demands when he said in a video posted on his social media channels: "I got something special for you. And by the way, all the money's in the bag so I expect you to be a man of your word."
The video then cuts to a previous interview with Joshua, who said: "I'll take 50million up front. If that's the case, Wilder's team bring me 50million up front and we'll take the fight."
Wilder then added: "I'll see you soon then."
The 32-year-old did not have to wait long for an answer from Joshua, who replied on Instagram underneath his fellow unbeaten fighter's video.
Shelley Finkel, Wilder's co-manager, confirmed the fee offered to Joshua, telling Sky Sports: "We made an offer to Joshua to fight Deontay in his next fight and we offered him 50 million dollars. He accepts it, it will be there. Al Haymon (Wilder's other manager) and I have never not delivered what we offered.
"I've made an offer, he can either accept it or not. He said 50million, that's more than double he's ever made. If he wants the fight, that's it."
Hearn admitted he will take the proposition seriously but is eager to find out more details and added he is yet to receive a contract.
The Matchroom promoter told Sky Sports: "We don't how real it is. Deontay Wilder's sent the letter and said 'you've got to sign the contract tomorrow and there's a fight'. We haven't had a contract yet. It's a wonderful PR move but we'll see.
"It's very nice of Deontay to make that offer, we need to see how secure that is, we need to see a contract, we want to know where it is and quite a lot of other things as well. But we're definitely interested to look at those numbers."