Goalkeeper Hugo Gonzalez was the hero, converting the winning penalty as America upstaged Atletico Madrid 3-2 in the shootout on Wednesday.
After a scoreless 90 minutes in Mexico, the Copa EuroAmericana clash was sent to penalties and America did just enough to edge the La Liga champions thanks to Gonzalez at the Estadio Azteca.
Atletico missed three successive penalties, having scored their opener, paving the way for Gonzalez, who also saved a spot-kick, to become an unlikely hero for the Liga MX side.
Gonzalez fired the ball beyond opposing keeper Miguel Moya to win the match and deny the Spanish club back-to-back penalty wins.
The Copa EuroAmericana - a friendly tournament consisting of thirteen teams from CONMEBOL, CONCACAF and UEFA - moved to Mexico for Atletico's second fixture and Diego Simeone made two changes to the team that beat the San Jose Earthquakes on penalties on Monday.
Teenage pair Lucas Hernandez and Saul Niguez replaced Emiliano Insua and Leo Baptistao, while first-team regulars Juanfran, Miranda, Gabi, Koke, Arda Turan and Raul Garcia retained their spots.
America - two games into their Apertura campaign and undefeated - and Atletico went head-to-head during the opening 45 minutes.
Both teams found themselves in goal-scoring positions but lacked composure and the final product as the match remained nil-all at the half-time interval.
It was the same problem in the second half, which was disrupted by wholesale changes, with opportunities for America and Atletico but nothing to show for it as the game headed to penalties.
And it was there where America emerged triumphant, stunning the Madrid-based outfit to win their only fixture of the Copa EuroAmericana in 2014.