[1] It was held on September 13, 2008 at the MGM Grand Garden Arena in Las Vegas, Nevada, U.S.[2] Márquez defeated Casamayor in the 11th round after two knockdowns, and captured his sixth world title in three different weight classes.
In the first four rounds of the bout, Márquez continually walked into counter punches from Casamayor.
Two minutes into the eleventh round, Casamayor was knocked down by a right punch as he pulled away from an intense exchange.
As soon as the action was allowed to resume, Márquez went in for the kill as he let his punches go in furious combination.
Referee Tony Weeks stepped in the bout, and stopped the fight as he deemed Casamyor unable to continue.