By Edward Chaykovsky

WBA 'regular' welterweight champion Keith Thurman has a lot of respect for Andre Berto, who previously held the WBC and IBF crowns at 147-pounds. The two fighters are both from the Florida area and represented by manager/adviser Al Haymon.

On September 12th at the MGM Grand in Las Vegas, Berto will challenge WBC/WBA welterweight champion Floyd Mayweather Jr. in the headline fight of a Showtime Pay-Per-View event.  

Berto, 3-3 in his last six fights, is a significant underdog in the contest with virtually nobody giving him a shot at what would be the biggest upset in boxing history. Some of the oddsmakers have Mayweather listed as high as an 80-1 favorite.

Berto lost bouts to Robert Guerrero and Victor Ortiz - and both of them immediately secured major fights with Mayweather. He was also set to face Shane Mosley in 2010, but withdrew due to personal reasons - and Mosley immediately secured a fight with Mayweather.

"There was a time in the boxing world where in my opinion, Berto was always like one fight away from fighting Floyd Mayweather. The first example was when he was supposed to fight ‘Sugar’ Shane Mosley and then the Haiti accident occurred and he went in and supported his fellow Haitians in their time of need over taking that fight. He had already accepted the fight but he had to back out of it due to the tragic accident," Thurman said to On The Ropes Boxing Radio.

"After that, when he fought Victor Ortiz, Ortiz fought Mayweather right after Berto. Berto fought Robert Guerrero and Robert Guerrero fought Mayweather right after Berto. So in my opinion, Berto was a potential opponent for Floyd for a long time."