Eddie Hearn has offered a glimmer of hope that Kell Brook-Amir Khan could still happen but warned Team Khan not to "insult" his fighter.
Talks over a world title fight apparently hit a brick wall last week when Brook and his father rejected outright the terms challenger Khan is demanding.
Those demands, according to Hearn, amount to a 70-30 split in Khan's favour despite the fact Brook would come into the fight as the IBF's welterweight champion.
Brook's father left the most recent meeting when those terms were put to him, but in another twist Hearn says the relationship between the two camps is "stronger than ever" as he continues to seek the "middle ground".
He told Sky Sports News HQ: "They felt like a 70-30 split was fair and that's a split normally you'd associate with a mandatory challenger for a world title Amir Khan doesn't have. We feel like the split should be 50-50.
"You're not talking about five per cent. Could I convince Kell Brook's dad to take five per cent less? Yeah, maybe, and you can get creative around these numbers, but 20 per cent is a borderline insult.
"I think [60-40] is too wide. That doesn't mean it's not a discussion that can be had and maybe then you move to 55-45, but for me Kell Brook has to be respected and get what's right. You can't just roll over and take a deal you can't accept."
Brook jumped two divisions to middleweight to tackle Gennady Golovkin in his last fight and made it clear after a brave defeat he sees his long-term future in the 154lb super-welter class.
And Hearn has warned Brook is already compromising by agreeing to take on Khan at 147lbs without giving further ground in the financial negotiations.
He said: "I think this is the right fight, but I will say I think 147lbs for Kell Brook is not a good move. He struggled to make that weight for a long time.
"We moved up to 160lbs and he made it really well. It was a little bit too much weight, but why deplete yourself when you can be a much better fighter at 154?
"He'll do that for Amir Khan because he wants it so bad, but what he won't do is have the mickey taken out of him. Is there a middle ground? Maybe, but I think now you're more likely to see that middle ground come later in the year."