Oxnard, CA. --- Two-division world champion Sergio Martinez (L) listens to his trainer Pablo Sarmiento (R) during training for his upcoming Mexican Independence Day Middleweight championship battle against undefeated WBC Middleweight Champion Julio Cesar Chavez Jr.  Promoted by Top Rank, Zanfer Promotions and DiBella Entertainment, in association with Wynn Las Vegas, At&T and Tecate, Chavez Jr. vs Martinez will take place Saturday, September 15 at Thomas & Mack Center in Las Vegas, live on HBO Pay Per View. Photos by Chris Farina/Top Rank.