Floyd Mayweather Jr. would "get smashed" by Khabib Nurmagomedov if the two boxers ever fought, says UFC's president Dana White.
Last week, White fueled speculation of a fight between the Russian and American boxers, but said it has to happen in the octagon.
Nurmagomedov, who recently beat Conor McGregor on his long-awaited return to mixed martial arts, triggered rumors of a mega-fight with Mayweather after calling out the former boxer.
The 41-year-old Mayweather, who came out of retirement for in 2017 to beat UFC's McGregor in a money-spinning boxing bout, has also teased the possibility of fighting for Nurmagomedov.
"Khabib would (win)," White told CNN Sport's Patrick Snell. "It would be a very ugly fight," he revealed. "Floyd would get smashed."
However, White insisted that the only way the fight can happen, is if makes the switch to UFC from boxing.
"This is where the money is," said White, directing his message to Mayweather: "You know it, I know it -- we all know it. Come fight in the UFC.
"Call me, Floyd -- you know how this works. Call me if you really want to get a deal done."
Mayweather has fought 50 professional fights without defeat; the younger Russian has a 27-0 record.
Brawl 'not our finest moment'
Speculation of a fight between the pair comes after the infamous brawl between Nurmagomedov and McGregor broke out last month.
"I was very upset after the event," said White, who admitted the post-fight chaos hadn't done UFC's brand any favors.
"I've been working on the sport for a long time, working on this brand for a long time -- (the bout) the biggest stage we've ever had and not our finest moment.
"Just because you're allowed to go in there (the octagon) and fight during a sporting event doesn't mean you get to do this stuff after, or before."
Nurmagomedov is currently suspended from fighting in the UFC after the ugly scenes that followed his fight with McGregor last month.
After forcing the Irishman to tap out, Nurmagomedov and his team launched an assault on McGregor and his team.
The Nevada State Athletic Commission, which governs the sport, unanimously ruled to uphold the fighters' suspensions last week until the end of its investigation.
"There's definitely no love lost between those two," White added. "They do not like each other. Their camps do not like each other.
"We've been doing this for 18 years and things like that don't happen -- obviously that was a very explosive situation," he said.
"We were prepared for it, and that's why the thing was handled in less that 40 seconds.
"We'll make sure it never happens again."