World super flyweight champion Martin 'El Gallo' Castillo of Hacienda Hts., California, will defend his world title against former champion Alexander 'El Explosivo' Munoz of Venezuela on Top Rank's big Erik Morales vs. Manny Pacquiao "The Battle" championship card hosted by Wynn Las Vegas at the Thomas and Mack Center, Las Vegas, on Jan. 21. Bob Arum of Top Rank made the announcement today. "The Battle," featuring Morales vs. Pacquiao and Castillo vs. Munoz, will be available on HBO Pay Per View. Two more televised bouts will soon be announced, Arum said. Castillo vs. Munoz is a fiery matchup. This will be the third WBA 115-pound world title defense for Castillo, 29-1 with 16 knockouts. Castillo won the world title from Munoz, 28-1, 26 KOs, one year ago in Laredo, Texas. In that fight, Castillo was an early-round aggressor and boxed effectively. He knocked down Munoz in the fourth and eighth rounds and won by decision. Since, Munoz has been on a rampage to get back at Castillo. Munoz has won three straight fights including a WBA eliminator victory over Julio Ler in Buenos Aires, Argentina on May 26. Those wins returned Munoz to the #1 position in the WBA ratings. Castillo, born in Mexico City, is a seven-year pro. He is managed by Frank Espinoza and trained by Manuel 'Chapo' Robles Sr.