Eddie Hearn has told ESPN that the delay in announcing a fight between Tyson Fury and Deontay Wilder could harm the chances of Anthony Joshua facing the winner in April.

WBA, IBF and WBO world heavyweight champion Joshua faces mandatory challenger Alexander Povetkin at Wembley on Saturday. A second Wembley date has been set for April 13, although an opponent has yet to be announced.

Talks with WBC champion Wilder about a potential unification fight fell apart in June, and the American is now set to face the undefeated Fury in the United States.

The pair met in the ring following Fury's win over Francesco Pianeta in Belfast in August, with promoter Frank Warren confirming that a fight would take place before the end of the year. But a date and venue have yet to be announced, and Hearn has admitted that the uncertainty may force Joshua to look at other options.

"We need to know if they [Wilder's camp] want the fight in April," Hearn told ESPN at Joshua's open workout at York Hall on Wednesday. "If Anthony beats Povetkin, we've probably got two, three weeks to make the Wilder fight -- otherwise we'll have to fight a WBO mandatory.

"It's frustrating, especially frustrating when people think that Anthony is stalling the fight or we're stalling the fight. We're ready to go. We've already sent a signed contract on the terms they agreed.

"Now they want to renegotiate the terms. No problem, just tell us the terms you want and we'll get it done for April. It's a lot of talk and not a lot of action from their side."

Fury's promoter Warren told IFL TV earlier this week that a press conference will take place in London on Monday, Sept. 24, with a promotional tour set to follow, though Hearn said he isn't convinced.

"I'm not sure that fight will happen," Hearn said. "I think it might get announced, but I'm not sure you'll see those two fighters in the ring.

"Listen, we hope they do. It's a good fight, and of course we want the winner, and that fight is even bigger. But it worries me when you announce a fight six weeks ago and still there's no news, no press conference, no anything."

Anthony Joshua works out with trainer Rob McCracken during a media workout on Sept. 19, 2018, in London. Justin Setterfield/Getty Images

If a deal cannot be agreed with either Fury or Wilder, then Joshua will be ordered to face a mandatory challenger for the WBO belt. There is a good chance that after his victory over Joseph Parker in July, that man could be Dillian Whyte -- who beat Joshua during the pair's amateur days but lost to him as a professional in 2015.

"He [Whyte] may end up being WBO mandatory, and it would be a great fight for British boxing," Hearn said. "He's earned it. He's beaten [Dereck] Chisora, beaten Robert [Helenius], beaten Parker and beaten Lucas Browne as well, so he's earned that No. 1 position.

"The first fight [in 2015] was sensational, and they were both so raw. If we can't get Wilder, Dillian Whyte is a front-runner."

But before he starts to think about future fights, Joshua must first get past Povetkin, who, like the Englishman, is an Olympic gold medalist.

"This is right up there with Joshua's fight against Vitali Klitschko," Hearn added. "The Klitschko fight was something else, but I expect a similar fight. Povetkin has excellent pedigree, he's an excellent technician, can really punch, very strong, very durable. He has a great team behind him that are desperate to win.

"Then for Anthony, there's the pressure. Talk of an undisputed fight next year, talk of Anthony being the best heavyweight in the world. So every time he goes out there, he's under massive pressure to perform. I think he feels that pressure in this fight, and I think he really wants to put on a great performance."