Oribe Peralta wrote his name into Mexican folklore with a deadly double against the five-time world champions, who many believed were destined finally to end their agonising wait for Olympic glory.
But despite Hulk pulling a goal back in stoppage-time and Chelsea new boy Oscar missing a last-gasp sitter, Brazil were a shadow of the attacking force that had smashed in 15 goals en route to the final and displayed the defensive frailty that has long dogged them.
In sharp contrast, Mexico completed their transformation from one of the most notorious also-rans in world football to a side capable of delivering on the biggest stage. And they could not have picked a better time than in front of 86,162 at the home of football in what was their first truly global major final.
Few would have predicted the fastest goal ever in a FIFA tournament final - also thought to be the quickest in Olympic history - after just 28 seconds. Manchester United right-back Rafael's hospital pass was intercepted by Javier Aquino and the ball broke for Peralta to race goal-ward unchallenged and fire home.
Brazil made an attacking change just past the half-hour mark when midfielder Alex Sandro was withdrawn for Porto team-mate Hulk. And the substitute almost caught out Corona with a piledriver from nearly 35 yards but the goalkeeper recovered well to foil Leandro Damiao's rebound.
Marcelo should have tested him again when he flashed wide from Damiao's lay-off and his timing was all wrong again moments later when he went through the back of Peralta, rightly earning a booking.
Leandro Damiao had a good chance nicked off his toe and powered a free header wide from a corner before Peralta rightly had a second goal ruled out for offside.
Fabian almost scored legitimately when he nodded over Jorge Enriquez's flick-on from a corner but made amends 15 minutes from time with a free-kick that Peralta netted with a bullet header thanks to simply non-existent marking.
Brazil should have staged an amazing comeback in stoppage-time, Hulk racing on to a long ball from Marcelo and rifling into the net before crossing for an unmarked Oscar to somehow nod wide from six yards.