MIAMI • Boxing great Floyd Mayweather was involved in a chaotic brawl on Thursday during the build-up to the June 6 fight with YouTube star Logan Paul, as tempers boiled over at a press conference in Miami.

The unbeaten former welterweight world champion (50-0) reacted angrily at the Hard Rock Stadium after Logan's brother and fellow social media sensation, 24-year-old Jake, grabbed his cap during a TV interview.

Mayweather, 44, chased down the Paul brothers and punches appeared to be thrown in a melee involving a scrum of security staff.

Mayweather unleashed an expletive-laden tirade during the incident.

Insults had already been traded in an earlier confrontation, with Logan taunting Mayweather by referencing his 2011 domestic violence case.

Mayweather served two months of a three-month jail term for attacking a former girlfriend.

He claimed he would fight - and beat - both Paul brothers on the same night before the event erupted into violence.

Logan had to be pulled away by his entourage, while Mayweather continued to vent his fury before he too was hustled away.

Before the brawl, Logan told Agence France-Presse he firmly believed he could do what no boxer had ever done before and beat Mayweather.

"After this fight, I don't want anyone to tell me something is impossible," the 26-year-old said.

"I am representing the guy who was counted out, the guy who believed in himself so much that his unrelenting belief in himself propelled him to success. That's me.

"I don't just think I can beat him. I know I can beat him."

Mayweather, meanwhile, accused the Paul brothers of failing to show him respect.

"You can't keep crossing the line, keep touching me, taking my hat off, touching my shoes," he said after the skirmish.

"I know how to sell a fight but you cannot cross the line.

"They can say certain things about me, I can say things about them.

"But what I won't do is push or touch anyone."

AGENCE FRANCE-PRESSE