That little piece of shit Mayweather would get OWNED in the octagon. Here's a list of fighters that would mop him up: Kenny Florian, Sean Sherk, Nick Diaz, Takanori Gomi, Jens Pulver, BJ Penn, Mach Sakurai, Gilbert Melendez, Shinya Aoki, Yves Edwards, Joe Stevenson, fuck man I could go on all day. Granted he has a PUNCHER's chance, but seriously he'd be taken down and pounded out, or submitted.