Julian Quinones lit the fuse in the 22nd minute, smashing home after Mexico had already rattled the woodwork through Santiago Gimenez and Raul Jimenez inside the first quarter of an hour. Ecuador had their own let-off when John Yeboah crashed a close-range effort against the frame of the goal, but it was as good as it got for the visitors.
Nine minutes later, Jimenez made his earlier miss count. He combined slickly with Quinones and buried the finish to send the Azteca into raptures at 2-0. Game over, in all but name.
Ecuador, back in the knockout rounds for the first time in two decades, threw men forward after the break in search of a lifeline. Sebastian Beccacece's side hurled cross after cross into the box, but there was precious little to show for it beyond a scuffed Kevin Rodriguez effort that never troubled Mexico goalkeeper Luis Malagon.
It got ugly late on. Moises Caicedo picked up a needless booking for a reckless lunge on Erik Lira deep into stoppage time, then Piero Hincapie saw red in the fifth added minute after mouthing off at Santiago Gimenez. A miserable night for Ecuador ended with ten men trudging off.
Mexico, meanwhile, are dreaming bigger. The win ended a brutal 40-year wait for a World Cup knockout victory on home soil, and the co-hosts remain unbeaten and unscored against in the tournament. They now wait to discover whether it will be England or DR Congo standing in their way in the last 16.
"I think the whole crowd is on their back, I think that gives them a lot of push. We had that same energy against Germany, so we kind of know how that feels. And yeah, obviously we're devastated," stated Ecuador midfielder John Yeboah.
Beccacece cut a dejected figure afterwards, but found the words to thank a nation that dared to dream.
"We were outplayed in the first half. Then we fought back, but we couldn't find the goal that would have given us a boost. I'm grateful to all the players and to the country for this journey and this adventure alongside them. I just want to say thank you."
Ecuador fly home having reached the World Cup knockout stage for the first time since 2006, a small consolation for a squad that came agonisingly short of springing a shock. Mexico, buzzing after finally breaking their knockout hoodoo, turn their attention to a last-16 date in front of another wall of noise at the Azteca.