Tyson Fury wants a potential crossover bout with Francis Ngannou to take place with 4oz gloves inside a cage in Las Vegas.
The 'Gypsy King' is currently the reigning WBC heavyweight champion but has frequently called out UFC's heavyweight champion.
Ngannou accepted the call on social media with the pair proposing different sets of rules for the bout.
Fury insists he plans to retire from boxing after his clash with Dillian Whyte at Wembley on April 23 - but said he will come out of reitrement to face Ngannou.
"I don't class that as a real boxing fight. That's going to be a special fight," he told The MMA Hour. "That will be in a cage with 4oz gloves in Las Vegas at the Raiders Stadium.
"He's a big guy; a big dangerous guy. People say it's not a fair fight in 10oz gloves and that's correct, because like [former UFC champion] Daniel Cormier said, Ngannou is a much cruder version of Deontay Wilder and we all know what happened there.
"So if we do it in 4oz gloves then he has more chance of knocking me out but I have a better chance of knocking him out also so it makes for an exciting fight. I will come in at my heaviest for that fight, I will be 300lb so that I can nail him to the canvas.
"He won't be the UFC champion anymore, I won't be the WBC heavyweight champion anymore, but I will still be the lineal heavyweight champion because they can't take that from me.
"It's very possible [that we see this fight in 2022]. I will have retired from competitive championship boxing and I will be ready to do the crossover fights."
Ngannou wants to switch from the cage to the ring and expressed his ambition publicly to take on the heavyweight division's best talent.
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Fury reacted to this posting on social media by calling out Ngannou after the Cameroon star claimed he could beat Fury in the ring.
Ngannou immediately responded by accepting the fight and vowed to make the fight happen after his successful title defence against Cyril Gane.
The 'Gypsy King' later proposed rules for any bout using boxing rules with UFC gloves, with Ngannou swiftly proposing the opposite by using MMA rules and boxing gloves.
The UFC champion admitted he would rather face Fury than any further defence of his belt against Jon Jones, but he will now face a nine-month period out of action after suffering a knee injury.
Ngannou had previously stated it is unlikely any bout will take place until 2023 as he recovers from injury and looks to resolve his contract issue with the UFC.
In any new deal, the champion has demanded an escape clause for any boxing fights so he is free to negotiate on the side of his octagon exploits.
