An unlikely hero stepped up late to help Jurgen Klinsmann's squad win south of the border for the first time in the rivalry's 75-year history
Although it was only a friendly, it was a historical night for the Americans, who entered the match with a 0-23-1 record in 75 years of competition south of the border.
Coach Jurgen Klinsmann did not select the team's biggest attacking threats - including Clint Dempsey, Jozy Altidore and Michael Bradley - but his defence kept the side at bay for long enough, allowing an unlikely hero to come in and ruin Mexico's Olympic gold-medal celebrations.
Fiscal, who plays for San Luis in Mexico, entered as a substitute in the second half, after the USA were quiet in advanced areas and throughout the game, and knocked one past goalkeeper Guillermo Ochoa.
The first half went back and forth with neither team carving out any real goalscoring opportunities, which could have initially been viewed at as a major accomplishment for the makeshift USA squad.
Playing with an experimental defense that featured Maurice Edu and Geoff Cameron at centre-back and Fabian Johnson at right-back, goalkeeper Tim Howard did not have to make a single save in the first half. He punched away a couple crosses, but that was about it.
USA may have been even less threatening on offense to open the game, however, and the teams entered the intermission scoreless. During halftime, Mexico's gold-medal winning team was honored on the field while fireworks went off around them.
The Americans' backline continued to deny Mexico from getting a good shot on goal as the second half went on. In the 55th minute, Cameron saved a potential goal when he got his head on a cross that was intended for Javier Hernandez about four yards away from the goal line.
Cameron was a key player for USA the entire night and showed why Stoke City decided to bring the former Houston Dynamo defender to the English Premier League this summer.
Mexico began to really put on the pressure in 75th minute when 'Chicharito' found himself free from the USA defence on a cross from Elias Hernandez, but his header went just wide of the net. It was a move that the Manchester United striker would have finished off during his breakout year in 2010-11.
But it would be the Americans to get on the scoreboard.
Shea surged past Severo Meza into the box and Boyd came up with the loose ball and applied a backheel pass to Fiscal, who was in the right place at the right time for the goal.
Mexico did not go out without a fight, but Howard was there to literally save the day.
In the 84th minute, Hernandez's shot from within the box was deflected, forcing Howard into saving a rolling ball right on the goal line. Moments later, Howard made perhaps an even better stop when the striker went up for another header, stopping the ball just inches from the line with his feet.