El Salvador beat Central American rival Guatemala, 1-0, to take second place in Group A at the Gold Cup and advance to the quarterfinals Sunday against the United States. Santos Cabrera’s goal in the 59th minute moved Cuscatlecos into the knockout phase of the Gold Cup for the first time in their history. Mexico, the winner of Group A, will meet South Korea in the other quarterfinal Sunday at the Rose Bowl. The Koreans were held to a 0-0 tie by Cuba but took second place in Group B behind the United States on better goal difference. The result, however, will do nothing to ease the concerns of the hypercritical Korean press about the play of this summer’s World Cup co-hosts. In Saturday’s quarterfinals, defending champion Canada meets Martinique and tournament favorite Costa Rica faces Haiti at Miami’s Orange Bowl.