Julio Cesar Chavez vs Floyd Mayweather at 140, both primes, who wins?

Chavez beat a lot of tough elite fighters at 140. These couldn't be said of Floyd Jr. who, in his whole career, hasn't fought top-caliber opponents, save for an aging Oscar de la Hoya and an overrated Ricky Hatton. Chavez was pound-for-pound king for a long time during the 90's. He was a highly-skilled boxer-puncher with tons of fighting heart, stamina and ring savvy. He was methodical in dismantling his opponents, usually going for the body (He was a deadly body-puncher) in the early rounds before taking off the head once their guard comes down. As de la Hoya said in a recent Ring article, "he's the complete package." Mayweather is an excellent and astute boxer with Willie Pep-like defense. He's very fast and very quick. But Chavez was also very patient. He'd keep on coming at and cutting off the ring on you 'til he could land his power blows. And once he finds his target, Floyd Jr. will go down. Chavez by UD or late round stoppage.