Midfielder Lucas Lobos put Tigres ahead in the first half of Saturday's match when he surprised fellow Argentine Federico Vilar in the Morelia goal by tucking a free kick inside the near post when the goalkeeper was expecting a centre into the crowded box.
Tigres' lead was cut to one point with second-placed Atlas beating title holders Tijuana 1-0 at home in Guadalajara city with a third-minute goal from striker Omar Bravo.
After nine matches, past the halfway stage in the 17-game league phase of the Clausura championship, Tigres have 21 points and Atlas 20.
America, who crushed Cruz Azul 3-0 with a hat-trick from Ecuador striker Cristian Benitez at the Azteca, have 19 points.
"My team came close to perfection. The most important word in football is balance and we managed that," America's coach Miguel Herrera told reporters.
The teams finishing in the top eight places of the league phase qualify for the knockout rounds.
Apertura championship winners Tijuana have 16 points in fourth place but Cruz Azul remain outside the top eight.