Dana White has promised to never work with Tyson Fury's promoter Bob Arum on an event, essentially shutting down a possible fight with Francis Ngannou.
Both Fury and Ngannou are signed to exclusive broadcast deals with ESPN in America and BT Sport in the UK, and have been angling for a fight with one another as the boxing and UFC heavyweight champions.
But White has never been keen on working with boxers for crossover fights, and has a long-standing disdain for Arum over his comments towards MMA.
And the UFC boss appears to have put an end to rumours of a bout between Ngannou and Fury by vowing that he won't ever put together an event with Arum.
"The fact that they [boxing world champions] are even talking about our guys shows you where boxing is at," White told Mirror Fighting after UFC 271.
"Boxing's been a mess for a long time and it's not going to get straightened out any time soon."
And he has said that working with Arum would be a dealbreaker on any potential event, despite being a fan of his rival promoters like Eddie Hearn and Al Haymon.
"I'm not doing jack s*** with Bob Arum," White insisted, seemingly shutting down a Fury collaboration.
"The other two guys I like, I like Al Haymon a lot and I like Eddie Hearn very much."
White has only once allowed one of his fighters to make the switch to boxing while under UFC contract; when Conor McGregor took on Floyd Mayweather in 2017.
The battle of two of combat sport's biggest stars proved one of the most lucrative events in fighting history, and he has said it would take similar numbers for him to do it again.
And Fury believes that should he get a fight with Ngannou, the current UFC heavyweight champion, the pay-per-view numbers would break boxing and MMA records.
Asked during the week about fighting Ngannou, he told iFL TV : "Not for this year, no because I've got boxing to do but next year we can have some f***ing crazy fights.
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"[It's] very big. I believe it breaks all pay-per-view records in the United States. Two heavyweight champions going head to head."
White holds what is essentially a monopoly on the top fighters in MMA, with UFC champions widely considered the best in their weight.
But in boxing there are two men with legitimate claims to the world heavyweight title; Fury holds the WBC and The Ring belts, while Oleksandr Usyk is the unified WBA, WBO and IBF champion.
Ngannou is currently set for surgery, and is at odds with the promotion over his contract.
And he has insisted that part of his next deal with White and the UFC would need to be a clause that allows him to box against one of Fury, Anthony Joshua or Deontay Wilder.
Joshua is promoted by Hearn, while Wilder works with Haymon and PBC.
