Hector Herrera scored a dramatic winner in the ninth minute of stoppage time to send Mexico into the Gold Cup decider against the United States after a tense 2-1 semi-final victory over Canada in Houston.
The Atletico Madrid midfielder fired in a low strike from the edge of the box after substitute Rodolfo Pizarro's cutback, clinching the win on Thursday.
Mexico defender Carlos Salcedo had seen his second-half penalty saved as Canada goalkeeper Maxime Crepeau came up with some big stops.
The reigning champions had taken the lead with an Orbelin Pineda penalty on the stroke of half-time, but Canada levelled from Tajon Buchanan with a low 57th-minute finish.
Mexico will now have a shot to claim a 12th Gold Cup title when they tackle six-time champions the United States in Sunday's decider. El Tri have won four of the past six Gold Cup titles and qualify for the final for the 14th time.
Two-time winners Canada were chasing their first appearance in a Gold Cup final since 2000 but miss out.
Canada forward Stephen Eustaquio fired over the bar early before Alistair Johnston desperately blocked off a Jesus Gallardo chance in the 27th minute.
Mexico won a penalty in first-half stoppage time following a VAR review on Doneil Henry's foul, with Pineda coolly sending Crepeau the wrong way.
New England Revolution forward Buchanan equalised 12 minutes into the second half, ghosting into the box and sliding a low shot past Mexico goalkeeper Alfredo Talavera.
Mexico then had a chance to reclaim the lead from the penalty spot after another VAR review, but Crepeau dived to his right to block Salcedo's effort.
Theo Corbeanu tested Talavera with a curling effort, before Crepeau made a point-blank save from a Mexico corner.
Mexico would find a way, with vice-captain Herrera's late winner.