Tyson Fury's UK-based promoter Frank Warren insists "our door is open" to agree "the fight he wants" against Anthony Joshua.
Fury (WBC) and Joshua (IBF, WBA and WBO) hold every major belt between them and Warren is in "ongoing talks" with promoter Eddie Hearn to stage a fight that would crown the undisputed champion of boxing's glamour division.
"It's not a difficult fight to make. Whatever is on the table is 50-50," Warren exclusively told Sky Sports.
"Fury is the No 1 heavyweight but we don't say 60-40. 50-50 down the middle.
"Once we get the offer that we're supposed to be getting, we'll be in a position to sit around the table and knock it into shape. It's not about me or [Joshua's promoter Hearn's company] Matchroom. It's about getting this fight made.
"If we can't make this happen between us, then we've got to point the finger at whoever doesn't make it happen."
Joshua is first seeking a UK location for his mandatory title defence against Kubrat Pulev, while Fury is contracted to a third fight with Deontay Wilder.
Fury previously told Sky Sports: "All going well, god willing, we get on the big fight with me and Joshua, the all-British showdown and I can give the fans what they want to see."
Warren said: "I'm very excited at the thought of this fight. But both fighters have contracts at the moment - AJ against Pulev and Fury against Wilder.
"If an offer came up, that the Pulev fight had to be avoided, or our contracted Wilder fight had to be avoided, then we need to make that happen. Let's get it on.
"We've been waiting for various offers. Nothing has arrived yet. There have been ongoing talks.
"Fury? I know I speak on his behalf - he wants the fight. More than anything, he wants the fight.
"I don't think Matchroom want the fight.
"All day long, Tyson Fury beats AJ.
"I had this conversation 18 months ago when Tyson came back. It's not an issue. This is the fight he wants.
"It's the first time ever four belts would be contested in the ring at heavyweight between two Brits. The No 1 heavyweight champion, undefeated, Tyson Fury is the most popular sportsman in the country at the moment."
Top Rank's Bob Arum, who promotes Fury in the US, exclusively told Sky Sports: "If Fury beats Wilder and if Joshua beats Pulev, which I don't want because [I promote] Pulev, then we would go ahead and do Fury vs Joshua next year.
"I don't think the negotiations would be fraught with difficulty. We could negotiate the deal, if we met in person, over the course of one day.
"We are not known for playing games. We understand Eddie. I worked for many years with his father Barry.
"My prediction would be: we get a deal done over the course of one day."
Joshua would "sign now" for two fights against Fury in 2021, Hearn previously told Sky Sports.
Warren replied: "There will have to be a rematch. But that's not an obstacle. There are no obstacles to stopping this fight happening.
"Our door is open. We've all signed a non-disclosure agreement. We're waiting for an offer.
"At our end, it is not a problem."
Joshua previously told Sky Sports: "Logically to prove yourself as No 1, I have to fight Tyson Fury. He has to fight Anthony Joshua.
"What it will prove, me and him fighting? There will be one dominant figure in the heavyweight division that will have all of the belts and become undisputed."
Warren insists their dream meeting would be one-sided in the WBC champion's favour.
He said: "Has AJ got a better jab than Fury? No.
"Is AJ a bigger puncher? I don't think so.
"Has he got a better chin? I don't think so.
"Has he got the hand speed or footwork of Fury? I don't think so.
"Tyson is so good in every department. When you saw him get off the floor from that punch by Wilder it tells you what he's all about."
Dillian Whyte, who is scheduled to next face Alexander Povetkin at a behind-closed-doors UK venue this summer, retains his status as Fury's mandatory challenger and is due to receive his shot at the belt by February 2021.
Whyte told Sky Sports: "If I was such an easy fight, why is he not in any rush to fight me?"