Eddie Hearn says Dillian Whyte is Anthony Joshua's most likely opponent at Wembley next April as a fight with Deontay Wilder "looks impossible".
Joshua will put his WBA Super, IBF, WBO and IBO belts on the line against Alexander Povetkin on September 22.
The Brit has signed a two-fight Wembley deal and a unification bout with WBC champion Wilder - who is set to come up against Tyson Fury in November or December - does not appear to be on the cards after he has faced Povetkin.
Hearn, Joshua's promoter, said a rematch with compatriot Whyte - who beat Joseph Parker on points last month - is a strong possibility.
Whyte and Joshua fought in a 2015 grudge match. In the early rounds, Whyte managed to hurt Joshua and had him in some trouble - but Joshua rallied, broke Whyte down, and then stopped him in the seventh round.
Since then, Whyte has had a good string of wins over a former champion in Parker, Dave Allen, former champion Lucas Browne, Dereck Chisora, and several others.
"As it goes right now, he's [Whyte] the favourite, because Wilder won't communicate with us, or his team," Hearn said.
"At the moment, that [Wilder] fight looks impossible, because how can we get it made, if they won't reply?"
Hearn says another battle with Chisora could be next for Whyte, although Dominic Breazeale and Jarrell Miller are also possibilities.
"Out of the three, it's the fight the British public want," he added.
"I think Chisora has earned the rematch, to be honest. He looked finished against [Agit] Kabayel and then he produced that performance against [Carlos] Takam from the gods. How can you deny him the opportunity of a rematch?"
Breazeale, who holds the mandatory position to Wilder's world title, was recently pushing for a crack at Whyte and a rematch with Joshua.