Floyd Mayweather Sr warns son to 'know when to quit'

Floyd Mayweather Jr puts his WBC and WBA welterweight titles on the line for his 49th - and what he claims will be his final - bout against Andre Berto on Saturday (fight expected to start 4am BST on Sunday).

There is already speculation that the unbeaten Mayweather, 38, will come out of retirement to go one better than Rocky Marciano's record of 49-0 - but Floyd Sr has warned his son not to extend his career for too long.

"You've got to know when to walk away, no matter how talented you are. Look at Ali, look at Joe Frazier, man, your body can only take so much," Floyd Sr told the New Jersey Star-Ledger.

"I fought too may fighters, trained too many fighters, watched too many fighters not to know how many of them do come back -- a year later, two years later. I can't say Floyd Jr won't quit and then come back."

Mayweather Jr, worth an estimated $400 million (£259 million), is one of the richest athletes in the world and says money has long stopped being a motivator for the man known as 'Floyd Money Mayweather'.

"Listen, he's got pockets full of money," Floyd Sr said. "He's proven that he's the best in the world and now with money and time, his life is going in the right direction — unlike some of those guys who felt they had to try again.''

"He don't need to fight again. I'm sayin', I don't know how he will feel, but what I'm sayin' is if he thinks it over and he wants to go after that Marciano record (one more victory and retire undefeated), I'm sayin', I don't think he needs it. But if he thinks he does, there is just one way to do it.

"That's to go do it the right away. Don't wait and be out there a year or two later ... rusty, reflexes gone ... because that's the way it happens. If you gotta, then do it now. If my son [is] gonna fight any more, I hope he fights in five or six months, because he's got to fight when he can win, fight when he's still mobile, not after a year or two away.

"He is the best defensive fighter in the world and his defense creates his offense. I don't want to see a day when he fights after a long layoff and that he's lost that part of it."