Undefeated WBC welterweight champion Floyd Mayweather Jr. (2nd L) of the U.S. poses with Robert Guerrero (2nd R), also of the U.S., during a news conference at the MGM Grand Hotel & Casino in Las Vegas, Nevada May 1, 2013. Mayweather will defend his title against Guerrero at the MGM Grand Garden Arena on May 4. In the background are Leonard Ellerbe (3rd L), CEO of Mayweather Promotions, and Oscar De la Hoya (3rd R) of Golden Boy Promotions. REUTERS/Las Vegas Sun/Steve Marcus (UNITED STATES - Tags: SPORT BOXING)