Brazilian defender Juninho slotted in a penalty to hand Tigres a 1-0 victory over Club America on Wednesday in Estadio Azteca in the first leg of the Liga MX 2017 Apertura semifinal.
The Tigres captain gave his team lead four minutes into the second half, after America defender Bruno Valdez was controversially adjudged to have handled inside the area.
Tigres had the better chances overall, with America keeper Agustin Marchesin making a fingertip save from Eduardo Vargas in the 14th minute and both Edson Alvarez and Guido Rodriguez forced into last-ditch tackles in the second half.
America's Mateus Uribe went close to equalizing with an overhead kick in the 85th minute, but the home side had zero shots on goal over the course of the match and now hasn't scored a goal in 279 minutes of Liga MX play.
The return leg is on Saturday in Estadio Universitario. America will need to score at least two goals, with the away goal rule in place.
Morelia hosts Tigres' city rival Monterrey in the other semifinal first leg on Thursday in Estadio Morelos.
Tigres are bidding to reach their third consecutive Liga MX final.