He ain´t no Kid Chocolate. :nono Anyway, that´s an interesting one. For one, Chavez has a style advantage here. With his high-workrate, pressure body-attacking style he is the perfect foil for someone using the shoulder-roll as a main defence. Floyd´s got better legs at the weight but Chavez was superb at cutting of the ring. Chavez would force PBF on the backfoot, trap him repeatedly and go to work with his left hook. In the beginningPBF will have huge success with his counterpunching combinations, even so Chavez will take the sting of most of them via blocking and/or rolling with them, but as the fight goes on Chavez bodywork and pressure will take it´s toll, Mayweather´s workrate will drop, he will get more flatfooted and his punches will lose their sting. That´s when Chavez will try to up the ante and get him out of there but it will be too late, fight´s soon over and Mayweather knows how survive. In the end Mayweather will have taken most early rounds, Chavez the late ones and the middle ones will have been very competative. Coin-flip.
Chavez does not beat Mayweather at 130, let's be clear folks. (I'm imagining Mayweather is young and fast at the time though). Close win.