The Mexicans outdueled Brazil 2-1 in front of a packed Wembley Stadium to earn their nation's first gold of the Games and send a warning message to the soccer world.
Oribe Peralta struck with the fastest ever goal in an Olympic final to stun Brazil after only 29 seconds and added another with 15 minutes left to provide a lead big enough to survive Brazil's inevitable late rally.
With the World Cup less than two years away, the victory was proof that Mexico can be a serious contender on the international stage. Olympic soccer, with its under-23 format, does not always translate into senior success, but Mexico's golden generation has been grown, developed and carefully managed for 10 years with the specific intention that they will one day help lift a major international trophy.
A gold medal in this sport might not mean quite the same as in some others, but this was mightily sweet for Mexico, a country that has made the knockout stage of the last five World Cups but lost in the last 16 each time.
"These players are comfortable with each other and comfortable in this team," said head coach Luis Fernando Tena. "When you have togetherness, special [things] can happen."
This win was indeed special and remarkable. Led by its young superstar Neymar, Brazil, despite having never won an Olympic title, was a huge favorite going into the game. Mexico refused to be overawed and clinched a triumph that was the culmination of a carefully pieced master plan.
After a defeat to the United States in the last 16 of the 2002 World Cup, the Mexican soccer federation started to take its youth program seriously, putting sufficient funding and thought into how to breed the next generation of stars.
As a result, players like superb young defender Diego Reyes and playmaker Giovani dos Santos have represented their country all through the various age groups and are now expected to play a key role in Brazil at the 2014 World Cup.
"We know what it means to play for Mexico," said dos Santos, whose injury kept him out of the final. "We know how to handle it and the future is very bright."
Mexico's dream start set the tone for its perfect outcome. In the opening seconds, Manchester United defender Rafael da Silva was caught out when he tried to play the ball inside instead of allowing it to go out for a throw-in. Marco Fabian pounced on it and slid a neat ball through to Peralta, who made no mistake with an accurate shot into the bottom corner for the most unexpected of leads.
Brazil, predictably, fought to get back into the game and dominated possession for much of the first half. There was no getting past Mexican goalkeeper Jose Corona, though, and frustration began to set in.
Brazil coach Mano Manezes took the step of bringing on powerful forward Hulk in the first half in an attempt to add some sting to the attack. But Mexico remained calm and added to its advantage on 75 minutes with Fabian crossing expertly from the right and Peralta adding his second with a perfect header.
Brazil had some fight left. Hulk managed to halve the deficit with a well-taken goal, but by then it was deep into injury time.
[ Photos: U.S. women's soccer team takes gold ]
Even so, Mexico had to survive one more attack, as Oscar headed over a golden chance when he was left unmarked five yards out from goal. Seconds laterm the final whistle blew and Mexico's players, coaches and a jubilant nation back home went into celebration overdrive.
Another Mexican triumph in two years' time would be a major surprise, but this is a soccer program that just got the ultimate confirmation that it is heading toward bigger things.
More Olympics coverage on Yahoo! Sports:
• Video: Spice Girls reunion headlines Olympic Closing Ceremony
• U.S. track medalists under fire for relationship with man banned from sport
• Top 10 U.S. athletes to watch at Rio Summer Games
- Sports & Recreation