LAS VEGAS, NV – SEPTEMBER 09: Boxers Floyd Mayweather Jr. (L) and Andre Berto face off during a news conference at MGM Grand Hotel & Casino on September 9, 2015 in Las Vegas, Nevada. Mayweather will defend his WBC/WBA welterweight titles against Berto on September 12 at MGM Grand in Las Vegas. (Photo by Ethan Miller/Getty Images)

LAS VEGAS, NV – SEPTEMBER 09: Boxers Floyd Mayweather Jr. (L) and Andre Berto face off during a news conference at MGM Grand Hotel & Casino on September 9, 2015 in Las Vegas, Nevada. Mayweather will defend his WBC/WBA welterweight titles against Berto on September 12 at MGM Grand in Las Vegas. (Photo by Ethan Miller/Getty Images)