Callum Johnson is out of his world title fight against WBO light heavyweight champion Joe Smith Jr in New York after contracting Covid-19.
The Briton was due to fight the American next weekend in his second bid to become world champion.
“It’s a real great shame for Callum,” promoter Frank Warren told BBC Sport.
“Hopefully we can get him back in, they may want to [reschedule the fight] in late spring. He worked really hard to get the opportunity.”
Promoters Top Rank are confident of finding a new opponent for Smith Jr.
Yarde next in line for world title shot?
The news will be a massive blow to Johnson, who turns 37 this summer and might struggle to convince Smith Jr to rebook their fight.
British light heavyweight Anthony Yarde is number one in the WBO’s rankings and Warren – who promotes both Yarde and Johnson – expects the London fighter to be next in line to take on the champion.
“If Callum doesn’t get his shot then Anthony Yarde is next,” he said.
“I’d love to do Joe Smith v Anthony Yarde in the UK. The WBO say there is a mandatory due and it’s going to be Yarde. He is the number one.
“Anthony looked so good in his last fight against Lyndon Arthur. We’ve got him down to fight sometime in March anyway. Fingers crossed.
“We’ll see what happens next week with Smith and how he comes through. Then go from there.
“I want to keep Anthony busy. We want to get the world title shot for him. The experience he’s gained since [fighting] Sergey Kovalev stands him in good stead. He really gives Smith so many problems.”
Yarde v Buatsi?
While Yarde will be focused on securing his second world title shot, Warren is still eager for his fighter to take on domestic rival Joshua Buatsi.
Buatsi suggested to BBC Sport in December that he would love to take part in an all-British light heavyweight tournament with the likes of Yarde, Dan Azeez and Callum Smith all stars in the division.
Warren wants to agree the fight with Buatsi’s promoter Eddie Hearn, as well as another string of bouts in 2022.
“We don’t even need a tournament, we’ll make the fight. It’s not a problem for us, let’s do it,” Warren said.
“We’ve been talking about this for years. There was the meeting with Eddie Hearn that never happened. There’s loads of domestic fights to be made.
“I want Zach Parker in with Chris Eubank Jr. Conor Benn is another. I’d love him to fight David Avanesyan.
“That’s a great fight and I think our man wins. I even said put Benn v Avanesyan on DAZN and I’ll pay Avanesyan’s purse. I’ve told Hearn’s people this.
“They won’t even have to pay Avanesyan and they can give Benn the money they would have paid Avanesyan.”