Terms have been agreed for Anthony Joshua to fight Deontay Wilder - but the Briton may walk away if contracts are not agreed soon, Eddie Hearn says.
Promoter Hearn said Joshua could fight Tyson Fury instead, while a third go at Andy Ruiz Jr is also on the cards.
Former two-time heavyweight champion Joshua has been strongly linked with fighting Wilder with a December date in Saudi Arabia touted in recent months.
"We've agreed the money, we've agreed everything," said Hearn.
Speaking to BBC 5 Live Boxing, Hearn, who has promoted Joshua since he made his professional debut in 2013, said: "We're waiting on the official contract, but we won't wait forever."
He said Saudi Arabia as a potential location had been complicated by "a change of environment in Saudi Arabia with the operators in boxing".
Joshua, 33, has picked up two victories this year over Jermaine Franklin and Robert Helenius respectively, following consecutive defeats to unified heavyweight champion Oleksandr Usyk.
"He [Joshua] is just training away but he wants Wilder," added Hearn, who said the 2012 Olympic gold medallist wants to remain active.
"If it can't be made, he wants to stay active. If he fights in December, that'll be three fights in eight months which is incredible for him."
However, Hearn believes a super fight between Joshua and WBC heavyweight champion Fury could still be in contention, should a deal with Skills Challenge Entertainment, who Hearn has been negotiating with for the Wilder fight, fall through.
"People keep saying he should have one more fight and then fight Wilder, but we don't think so. If it ends up that way, so be it and nothing would surprise me," said Hearn.
"If he fights in December, if he fights Deontay Wilder, if he fights Tyson Fury next - nothing would surprise me."
The boxing promoter confirmed that Joshua will more than likely fight outside of England and has mentioned old rival Ruiz Jr as one potential opponent.
"There's Filip Hrgovic and there's Andy Ruiz Jr, but it probably won't take place in this country," added Hearn.
"He's had two now on the spin at The O2 Arena, so maybe we go to Madison Square Garden, somewhere in the Middle East. It's just about activity for him."
Joshua avenged his defeat to Andy Ruiz Jr in Saudi Arabia in 2019 after the Mexican sensationally knocked him out in New York at Madison Square Garden.
Eubank Jr v Benn talks are back under way
Hearn has confirmed Conor Benn and Chris Eubank Jr are in talks to reschedule their fight before the end of the year.
The pair were set to fight last October but the bout was cancelled after Benn failed two voluntary tests for female fertility drug clomifene.
"Eubank Jr v Benn is not as big as Tyson Fury v Anthony Joshua but it's not a million miles away," Hearn told 5 Live Boxing.
Benn, who currently does not hold a boxing licence in the UK, and Eubank Jr agreed to fight at a catchweight of 157lb, 30 years after their fathers Nigel Benn and Chris Eubank Sr famously fought.
"It's an all-time British classic, it's the biggest fight for Eubank Jr and it's the biggest fight for Benn," added Hearn.
"Hopefully we can get that done for December. We're in talks with Kalle Sauerland [Eubank's promoter]."
Benn, 26, had his provisional suspension lifted by the National Anti-Doping Panel, but this decision has been appealed by UK Anti-Doping and the British Boxing Board of Control.
"He's cleared to fight everywhere at the moment, he's not suspended, he's had that suspension lifted, he won his case," Hearn said.
"The British Boxing Board of Control are appealing and that's expected to be later this year but as of now, he's free to fight in the UK, he's free to fight in America, he's licensed in America as well, there are discussions about him jumping on the September 30th card in London, but there's also discussions about him fighting in Orlando on September 23rd."
Benn and Eubank Jr were booked to fight at The O2 Arena last October but Hearn says Wembley Stadium is being looked at as a possible venue.
"Eubank Jr v Benn is an absolute monster and that's why we're looking at Wembley Stadium."