Mexico head coach Sergio Almaguer made a number of changes to the lineup that had thwarted Curacao in the opener on Tuesday by the same 3-0 result. From its end, El Salvador came out aggressively approach, looking to close down as quickly as possible.
El Tri opened the scoring through Jesus Escoboza in the 14th minute. Julio Gomez delivered a delightful cross after making a long run down the right flank that the Necaxa midfielder headed towards the net from inside the six-yard box. Salvadoran goalkeeper Rolando Morales and Romel Mejia each made desperate attempts to halt the ball from crossing the line, but could not prevent their team from falling behind.
Morales did craft a miraculous save 20 minutes later, acrobatically flinging himself across the face of the goal to make a one-handed stop off another header by Escoboza.
Mexico emerged from the break determined to make its possession advantage pay. After some back-and-forth moments to begin the half, it doubled its lead in the 52nd minute through Gomez, who headed in a Francisco Flores free kick.
An own-goal by El Salvador's Olivier Ayala with five minutes to play completed the score line, sending the Mexicans into the quarterfinal round with maximum points from two group matches.
Mexico will face Jamaica on Wednesday in one quarterfinal, while El Salvador - also through to the quarterfinals by virtue of a 2-1 victory over Curacao on Thursday - faces Panama in another. The winner of each of those matches earns a berth in the 2013 FIFA U-20 World Cup in Turkey.