Eddie Hearn, promoter for IBF, IBO, WBA, WBO heavyweight champion Anthony Joshua (21-0, 20 KOs), has issued a warning that he already has a backup opponent for his boxer's planned fight on April 13 at Wembley.

Hearn is trying to secure WBC heavyweight champion Deontay Wilder (40-0, 39 KOs) for the April date.

If Wilder does not agree to the terms, then Hearn will make the rematch between Joshua and Dillian Whyte - if Whyte is able to defeat Joseph Parker later this month.

Back in 2015, Joshua stopped Whyte in the seventh round of a fireworks filled fight. Whyte had Joshua hurt in the early going, but he was broken down as the contest played out.

According to Hearn, he has no intention of improving Wilder's offer for the April fight.

Wilder believes that at least a 50-50 split should happen - and that scenario is never going to happen.

For the moment, Joshua will return to the ring on September 22nd, when he makes a mandatory defense against Olympic gold medal winner and former world champion Alexander Povetkin.

And Hearn views that contest as a very dangerous proposition with the possibility of an upset.

"I know there’s a lot of talk about Wilder but this [Povetkin defense] is the toughest fight of Anthony Joshua’s career,” Hearn told IFL TV.

“This is the sixth defence of his world heavyweight title, it’s an incredible achievement.

“This is all about unifying and becoming the undisputed champ. He wants to walk through Povetkin and then smash Wilder to smithereens.

“We won’t be improving the Wilder offer. If Whyte beats Parker and Wilder doesn’t want Joshua then we’ll just do Joshua-Whyte.

“But Joshua has got a tough fight in Povetkin and we can’t look too far past that.”