Marcelo Balboa scored in the 75th minute to give the USA a 2-0 lead over El Salvador.
Balboa scored on a pass from Alexi Lalas after a chip into the box by Claudio Reyna.
Steve Sampson has used all three substitutes: Paul Caligiuri for Thomas Dooley, Jovan Kirovski for Eric Wynalda, who scored the first USA goal at the 62nd minute, and Reyna for John Harkes.