Floyd Mayweather got involved in a scuffle with Jake Paul at a media event for his upcoming exhibition fight against his brother Logan Paul.
Mayweather, who retired from the professional game with a record of 50-0, faced off against the YouTuber ahead of their Miami showdown at the Hard Rock Stadium on June 6.
Paul's younger brother Jake confronted "TBE" in front of the cameras and things soon escalated.
Following an exchange of words, things soon Jake Paul snatched Mayweather's baseball cap from his head and all hell broke loose.
Having put Jake Paul in a headlock, security had to intervene and pull Mayweather away.
"I'll kill that motherf*****. When I catch you I'm going to kill you," Mayweather shouted to Jake Paul, who was left with a black eye from the brawl.
The YouTuber, who also got confronted by Daniel Cormier at UFC 261, is looking for his next opponent having most recently defeated Ben Askren.
"Jake wanted to ask for his hat for his collection but Floyd wasn't happy about it because it's his favourite hat," Logan Paul said.
"I think its pretty f****** serious. I didn't expect Floyd Mayweather to try and kill my brother with all the security guards there."
He later added: "He told me he was going to do it and I told him not to.
"This s*** is so personal; this s*** was going to be kind of cute and we were going to put on a good show but now it's going to be a f****** fight, it's going to be a war.
"Floyd looked pretty emotional, he can act cool all he likes on stage but I think my brother is doing my job for me."