Anthony Joshua will face the winner of December's fight between Deontay Wilder and Tyson Fury "subject to terms, without a problem in the world", says Matchroom Sport chairman Barry Hearn.
Joshua retained his world heavyweight titles with a seventh-round stoppage of Russian Alexander Povetkin on Saturday.
He will return to Wembley in April to face a yet to be named opponent, with Dillian Whyte also in the frame.
WBC champion Wilder takes on Briton Fury on 1 December.
IBF, WBO and WBA champion Joshua confirmed after beating Povetkin that his "number one choice would be Wilder".
"We have sent Wilder a signed contract already to fight on 13 April. We will agree terms with Wilder to fight on 13 April if he beats Tyson Fury - if he does not beat Tyson Fury, we have got to look around as we have got a business to run," Hearn told Sportsweek on BBC Radio 5 live.
"Tyson Fury will not be in a position to fight on 13 April in my opinion. If he is, I would love to see it."
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Fury's promoter Frank Warren refused to confirm whether there was a rematch clause in the contract with Wilder, leading Hearn, whose son Eddie promotes Joshua, to say: "There has to be a rematch clause. Deontay Wilder is not going to risk his title without a rematch clause.
"I know Anthony Joshua has made his shopping list of who he would like to fight next and that is Deontay Wilder, but that is not to say the deal can be done."
Warren insisted former champion Fury would demand a 50-50 split of the purse for a fight with Joshua.
"It is subject to terms because you [Warren] will ask for a ridiculous amount of money and it won't be made," responded Hearn.
"It is not a 50-50 split against the number one heavyweight in the world - you can forget that completely."
'If I was you Joshua, I would avoid me'
Fury has fought, and won, twice since making his comeback in June after two and a half years out of the ring. During his spell on the sidelines, he gave up his world titles and focused on mental health issues.
"I think it is safe to say that neither Team Joshua or Matchroom will fight the Gypsy King. They mentioned if it is not Wilder, it will be Whyte, but there was no mention of Tyson Fury, the lineal champion of the world," Fury said in a video on social media.
"It is all right fighting men 39-year-old and half your size. [This] is the best evidence that I am fighting the best heavyweight out there in Deontay Wilder, Joshua is not even close. He is slow, methodical, ponderous at times, powerful yes, but they all are."
- Listen to 5 live Boxing at 21:00 BST on Monday as Mike Costello and Steve Bunce give their verdicts on Joshua's performance
Fury, Wilder or Whyte? - analysis
BBC Sport boxing correspondent Mike Costello: "13 April back at Wembley is an absolute definite. We still don't know who's going to be in the opposite corner. It was interesting what Eddie Hearn was saying that if Fury wins there will be a rematch because that will be in the clause - but if Wilder wins, he can sail on and that might mean Joshua [at Wembley] and this place won't be big enough.
"It was interesting that Eddie said Joshua versus Wilder is a bigger fight than Joshua versus Fury. If Fury beats Wilder, that fight against Joshua becomes even bigger than we're talking about."
BBC Radio 5 live boxing expert Steve Bunce: "According to AJ and Eddie, they have to agree the Wilder fight in the next couple of weeks. No-one wants to wait until December because it takes a long time to negotiate with Wilder's people.
"I don't think Dillian Whyte against Anthony Joshua on 13 April is a bad fight, but people might because they are used to something different. They want Wilder. People who have never heard of Wilder want Wilder.
"What if Fury goes and does a job on Wilder? The Gypsy King, the Dance Master…can you imagine? Three fights into a comeback.
"Joshua against either of those two is as good as it can get. It's going to set gate receipt, pay-per-view and endorsement records."