David Haye has a fight against a secret heavyweight legend teed up after his comeback against Joe Fournier, says promoter Ryan Kavanaugh.
Haye, aged 40, ends his retirement to take on Fournier on Saturday night, alongside Evander Holyfield's return against Vitor Belfort.
"It's not a comeback," Haye previously said to Sky Sports, who have now been told of secretive talks to pair him with an exciting rival in a future fight.
"If he wins? All I can say without giving too much away is that you should expect a very big fight," Triller promoter Kavanaugh told Sky Sports.
Haye has already vowed "not to make any decisions when the adrenaline is flowing after you've just beaten someone I'm a 100-1 favourite to beat".
He said about another fight: "I don't see that happening at all."
And he promised not to accept a second fight in the heat of the moment: "Definitely don't make any decisions right there."
But the crucial decisions may have already been made.
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Who is this mystery heavyweight that Haye is in talks to face?
"I couldn't tell you who it is," Kavanaugh teased.
Is it a British or American fighter?
"Both are on deck."
Mike Tyson, Evander Holyfield or Lennox Lewis?
"It may be."
Is it an old rival from Ukraine?
Is it a boxing great or someone from the world of entertainment?
"The highest of the high."
So that means a former world heavyweight champion?
"If that is what you consider the highest of the high? You wouldn't be wrong."
Sky Sports asked Haye about facing Tyson who, then 54, made a comeback last year in an exhibition bout with Roy Jones Jr.
"I don't want to start thinking about stuff like that," Haye said.
"Let me just get Joe out of the way. I need to go back on holiday!"
But Kavanaugh has insisted "it will be The Hayemaker that you know" inside the ring on Saturday.
A fight agreed at a party in Mykonos
Haye's opponent Fournier is undefeated in nine fights as a light-heavyweight.
His social media is flooded with selfies alongside A-list celebrities and he is in "the restaurant and bar business", at the pinnacle of hospitality on the holiday island of Mykonos.
It was at a party with his long-time friend Haye that a fiery dispute led to this weekend's fight.
Promoter Kavanaugh explained: "Everybody knows Joe and David have, or had, a friendship. Joe was trained by David, taught to box by David. Everything he knows is from David.
"Joe is younger, richer, more popular in terms of social media.
"Joe called me and said: 'I want to call out David Haye - he thinks I'm getting too big for my boots!'.
"I said: 'You are, bro!'.
"I'm not joking - Haye told Joe: 'Don't get too full of yourself because I could still kick your ass!'.
"But Joe said: 'No you couldn't!'.
"I said: 'Let's take this into the ring!'.
"Haye said to Joe: 'I am going to destroy you'.
"Joe said: 'You are old, I am young, you will get knocked out'.
"It became a contentious thing.
"David said: 'Listen buddy, I taught you everything you know'.
"And Joe said: 'You've got a bad [ankle], you are old and slow, I am going to knock you out'.
"They both say they will knock the other out with such conviction. They will be going full throttle.
"They're friends? That's what makes this so crazy!
"If David loses to his protege who fancies himself as a billionaire playboy? If Joe loses with all his trash talk?"
Sky Sports Boxing schedule
Oscar Valdez vs Robson Conceicao - WBC super-featherweight title
September 25 - Sky Sports Box Office
Anthony Joshua vs Oleksandr Usyk - IBF, WBA, WBO heavyweight titles
Lawrence Okolie vs Dilan Prasovic - WBO cruiserweight title
Chris Eubank Jr vs Sven Elbir
David Avanesyan vs Liam Taylor - European welterweight title
Richard Riakpohre vs Krzysztof Twardowski
Mikael Lawal vs Steven Ward
Savannah Marshall vs Lolita Muzeya - WBO middleweight title
Hughie Fury vs Christian Hammer
Jamel Herring vs Shakur Stevenson - WBO super-featherweight title
Josh Taylor vs Jack Catterall - undisputed super-lightweight title