Floyd Mayweather Sr hit the deck hard after an impromptu sparring match at his boxing club in Las Vegas.
The 66-year-old trainer took on former boxer and coach Ross Thompson, 45, but it did not go to plan.
After a bout of trash talking outside the ring, the pair decided to step inside the ropes with the younger man making light work of Mayweather Sr.
Thompson unleashed a fierce combination of punches that sent his opponent crashing to the canvas and silenced Mayweather Sr.
The encounter was filmed by an onlooker, who did not wish to be named, but said: “They were having a bit of a trash talk outside of the ring.
“Ross told Floyd Senior that his brother Roger Mayweather was a better trainer than him, so Floyd Senior got mad at that and so he threw a few shots about Ross’s career.
“Then Floyd told Ross that he wouldn’t be able to touch him, because he’s too big… like ‘you won’t be able to touch me, I hope I don’t hurt you’ then they got in the ring and went for it.
“It was really macho, it was great.
“They dodged each other in the ring for a bit, next thing you know Ross put a combination together and Floyd goes down, that’s a sequence of punches, almost like when you’re dancing and you have a sequence of steps, they were pretty fast and it got Floyd Senior laid out on the ground.
“He wasn’t quite unconscious, he was just went down hard, I’d say he was lying dazed on the floor for about 30 seconds after he hit the ground.
“Then he got up, we were all laughing and talking cra*p…they wound up shaking hands in the end.”
Thompson, meanwhile, said: “We were getting into it at the club, we have a history, he likes to trash talk at me.”
Mayweather Sr, a former fighter, has made his name as the father and trainer of undefeated Floyd Mayweather Jr during his legendary career.