Juan Román Riquelme
With the Argentina Under-20 team, Muñoz won the 1997 FIFA World Youth Championship in Malaysia, being teammate of players like Juan Román Riquelme, Esteban Cambiasso, Luciano Galletti, Diego Placente, among others. He was substitute of Leo Franco during the tournament and played in the second round against England under-20 team, in a game that finished in a 2–1 win of his country.