By Edward Chaykovsky

Mayweather Promotions CEO Leonard Ellerbe is promising a different Floyd Mayweather Jr. (48-0, 26KOs) on September 12th, when the pound-for-pound king defends the WBC/WBA welterweight titles against Andre Berto in the main event of a Showtime Pay-Per-View.

He says Berto was selected because of his aggressive style, to make Mayweather brawl it out in a very exciting fight to close out his 19-year career.

"He's never, ever been in a dull fight," Ellerbe said of Berto to Mlive.com. "He's been in two fight-of-the-year candidates, with the Ortiz fight and the Guerrero fight. We know he's been knocked down but he gets back up and fights his heart out."

"We already know we're going to get the best of the best from him, what he's able to do. And one thing you do know is it's guaranteed excitement. So with that, I think you're going to see a totally different kind of Floyd, too, because Berto fights in a very aggressive, offensive manner, and it kind of forces you to do other things."

Fans have heard promises of Mayweather going for a knockout in the past. Ellerbe says Mayweather did not take a step back in the May mega-match with Manny Pacquiao and he won't take any steps back with Berto.

"Floyd didn't take a step back in the Pacquiao fight, so what makes anybody think he's going to take a step back in this fight? And the other guy's fighting the same kind of way," Ellerbe said.