Club León saw Rubens Sambueza shown red, but held out to advance to the 2019 Liga MX Clausura Final.
Club América came into the match knowing they needed to score twice to have any chance of overturning the tie, and they opened the scoring early when Bruno Valdez appeared unmarked from a corner to head in the goal.
A brilliant save from Rodolfo Cota denied Guido Rodriguez a second, and by the end of the second period, there was no escaping the fact that Club América was the better team.
León improved after the break, and an Angel Mena cross floated dangerously across the Club América box.
In the 76th minute, referee Cesar Arturo Ramos, who deserved heavy criticism for his first half performance, got a decision right when Rubens Sambueza was sent off for a second yellow, leaving Club León town to ten men for the last 15 minutes of the match.
Miguel Herrera wrung his final change by bringing on an additional striker in Henry Martin, but las Águilas would receive a big blow late in the match when Guido Rodriguez was also sent off for a second yellow.
As Club América mounted forward in search for the winner, León created several openings on the counter, with Ivan Rodriguez coming closest to doubling the lead.
At the end, Club América failed to find a winner, while León saw out the victory to move one step closer to the title.
Club León will now take on Tigres in the 2019 Liga MX Clausura Final.