Zamora was the third former Chivas USA youth player promoted to the MLS club's first-team roster, alongside Gerson Mayen and Jorge Flores.
Mayen and Flores are with the U-20s for their trip to the Copa Ciudad de Rosario. Flores also played with the U-20s in Concacaf qualifying for the Under-20 World Cup, beginning in late September.
U.S. U-20 Roster:
GOALKEEPERS: Josh Lambo (FC Dallas), Brian Perk (UCLA)
DEFENDERS: Gale Agbossoumonde (unattached), Jorge Flores (Chivas USA), Ike Opara (Wake Forest Univ.), Anthony Wallace (FC Dallas), Sheanon Williams (unattached), Cesar Zamora (Chivas USA)
MIDFIELDERS: Danny Cruz (Houston Dynamo), Dilly Duka (Rutgers), Gerson Mayen (Chivas USA), Brian Ownby (Univ. of Virginia), Dillon Powers (Andromeda), Michael Stephens (UCLA)
FORWARDS: Sam Garza (University of Denver), Fuad Ibrahim (Toronto FC), Tony Taylor (Jacksonville Univ.)