Floyd Mayweather said Wednesday that he is more likely to end up in movies than keep boxing, as he rounded on his critics ahead of what he insists will be his last fight.

The unbeaten pound-for-pound king takes on massive underdog Andre Berto on September 12 in Las Vegas in a welterweight world title showdown that has so far failed to capture the public imagination.

The brash American, 38, will make it 49-0 with victory -- equaling the record of heavyweight legend Rocky Marciano -- and has consistently said he will hang up his gloves afterwards. Few believe him.

In a conference call with reporters, Mayweather and Leonard Ellerbe, CEO of Mayweather Promotions, said there had been "signficant" entertainment possibilities for the champion for when he calls it quits -- including three "major" movie offers in the last week alone.

"I've been approached on numerous occasions (to act) but I'd rather be behind the scenes. I've had my time to shine," said Mayweather, reiterating Berto would be his last bout and he is having no second thoughts about giving up the fight game.

Boxing fans and pundits have hit out at the self-styled "Money" and "TBE" ("The Best Ever") Mayweather's choice of Berto (30-3), who has lost three of his last six fights and was cherry-picked ahead of more exciting -- and more dangerous -- men.

"When you are in my shoes, they are always going to criticize, that comes with the territory," said Mayweather, the highest-earning sportsman in the world.

"I couldn't care less. Nobody is forced to watch. Watch if you want to watch, don't watch if you don't want to watch. Write about it if you want to write about it, if you don't want to write about it, don't."


Nothing to lose


The experts may have written off Berto, 31, but Mayweather insists he is taking his opponent seriously and says he is training harder for the rank outsider than he did for his so-called "fight of the century" against Manny Pacquiao earlier this year.

Mayweather extended his unbeaten run with a unanimous points decision over the Filipino in a disappointing bout.

Underestimating Berto, an aggressive fighter who is likely to be on the front foot against the defensively brilliant Mayweather, would be a dangerous mistake, said the champion.

"He has nothing to lose and when you have a guy that has nothing to lose, that makes him work that much harder," said Mayweather.

"He's got a chance to be the top guy in the sport when I'm through...anythingcan happen (in a fight) so I'm prepared and in top shape, as I'm sure he is.

"But I'm not going to overlook this guy."