Justin Bieber did everything but put on gloves and throw some punches to help defend his pal Floyd Mayweather Saturday night when the super welterweight champion took on Saul 'Canelo' Alvarez at the MGM Grand Hotel.

Biebs was in the locker room with Mayweather before the right began, and walked behind him all the way to the ring.  He and fellow Mayweather groupie,