Mexico lead Brazil 1-0 at half-time in the gold medal match between the two sides at the Olympic Games.
The Mexicans stunned their opponents by taking the lead inside the first minute. Oribe Peralta latched onto a loose ball outside the penalty area and curled his shot beyond Gabriel.
Fernando Luis Tena's side outplayed a sluggish Brazil in the opening stages, with Hector Herrera, Marco Fabian and Javier Aquino looking dangerous.
Brazil's first chance came with just under 15 minutes on the clock when a looping cross found Thiago Silva in the box, but he could only direct his header over the crossbar.
Mano Menezes's team came even closer to drawing level five minutes later. Damiao played in Oscar, who failed to trouble the keeper after pulling off a deft turn.
Brazil soon tightened up at the back, yet looked short of ideas going forward. Hulk was brought on in place of Alex Sandro to boost their front line, and he almost drew his side level on 37 minutes.
The Porto forward's long-range strike was palmed away by Jose Corona, but his teammates failed to pick up the rebound, leaving Brazil trailing at the interval.
