Eddie Hearn says a new opponent for Anthony Joshua will be confirmed by the end of the week.
A four-man shortlist of candidates are still in contention to face the heavyweight king on June 1 after Jarrell Miller failed a drugs test.
Andy Ruiz has emerged as a front-runner alongside Michael Hunter, with Manuel Charr also amongst those in contention.
But Luis Ortiz appears to have priced himself out of the fight, with Hearn revealing he rejected an offer of more than $5million amid claims from Boxing Scene he wanted a huge $10m purse to take the fight.
Hearn has confirmed discussions are taking place with Ruiz for a battle he believes would be a solid alternative for Joshua's long-awaited US debut.
Yet he admits plenty of names are still in the frame with offers on the table they could accept at any moment.
"There are discussions with his (Ruiz) team," Hearn revealed in an interview with Mixed Combat Radio .
"He's one of four guys right now I would say are front-runners.
"It's really about who takes it first. Any one of these guys can phone up and accept a deal and we could get it done tonight, but it will be in the next 48 hours for sure.
"It's not easy, because I think we live in a crazy world right now where everyone wants crazy money just to be in fights.
"I like the fight for many reasons.
"Aesthetically, Andy doesn't always look the best, but he can fight.
"He's fast, he'll be there to win, he's going to have a big Mexican support."
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Ruiz challenged for the WBO heavyweight title against Joseph Parker in December 2016, suffering the only defeat of his 33-fight professional career via a split decision.
He has since reeled off three straight wins, including a five-round demolition of German fighter Alexander Dimitrenko last weekend.