Mexico missed a second-half penalty before Hector Herrera netted late to keep their bid for a 12th Gold Cup alive.
Qatar missed a second-half penalty as USA qualified for their 13th Gold Cup final as they chase their seventh title.
Matthew Hoppe's first international goal gave the United States a Gold Cup victory over Jamaica.
Gold Cup holders Mexico cruised into the semi-finals after goals from Rogelio Funes Mori, Jonathan dos Santos and Orbelin Pineda.
Mexico claimed the win they needed to top Group A, with full-back Luis Rodriguez getting forward for the decisive goal.
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