By Dan Ambrose: WBC middleweight champion Julio Cesar Chavez Jr. (46-0-1, 32 KO’s) had better enjoy his win over Andy Lee while he still can, because on September 15th, Chavez Jr. is going to be in with a much different fighter in Sergio Martinez (49-2-2, 28 KO’s) in this fight at the Thomas & Mack Center in Las Vegas, Nevada.