The rematch between Erik Morales and Manny Pacquiao on January 21, 2006 in Las Vegas, Nevada provided another opportunity to feature Castillo on the PPV undercard, this time as the chief supporting bout to the main event. Castillo was rematched with Muñoz, who had won three fights since losing his belt. This time Muñoz came much better prepared, applying pressure from the opening bell and dropping Castillo in the first round. Castillo also suffered bad cuts over both eyes as the fight progressed. The aggressiveness of Muñoz and his heavy punches won him the early rounds. However, Castillo rallied in the later rounds, using better technique and counter-punches, but also exhibiting aggressiveness. The last three rounds featured furious exchanges between the fighters, with Muñoz growing increasingly tired, but still launching dangerous power punches.