And Boyd nearly scored twice more. His header went over the crossbar in the 10th minute, and he had a breakaway chance in the 11th only to see keeper Yimy Cuellar come out to break up the play.
Hamid rolled covering up a ball and appeared to hurt his ankle midway through the first half.
El Salvador took advantage by scoring two goals in two minutes to grab the lead and the momentum. Blanco scored on a header off a corner kick over Hamid's hands in the 35th minute, and Flores beat Hamid in the 37th minute off what had been a weak shot by Alas that turned into a cross. Porter pulled Hamid in the 39th minute, putting in 6-4 Johnson for his first appearance in the tournament.
Boyd tied it up with his second goal off a pass from Adu in the 65th minute. Corona, whose mother is a native of El Salvador, scored off a header just inside the left post off a pass from Adu.
Johnson smothered one strong kick from Isidro Gutierrez, but couldn't stop the ball when it mattered at the end.
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