Andres Ibarguen's late winner secured a 2-1 victory for Club America against nine-man Pumas on Saturday to book Las Aguilas' place in the Liga MX 2018 Clausura semifinal.
Second-seed America defeated seventh-seed Pumas 6-2 on aggregate in a comfortable series win, although it will have to wait until the other quarters are over to find out who it plays in the semis.
Coach Miguel Herrera's side resisted Pumas' initial attacks in Estadio Azteca and took the lead in the fourth minute, when Colombia international Mateus Uribe finished from a squared pass from French forward Jeremy Menez.
Uribe was once again player of the match and further strengthened his claim for a place in Colombia's team at the World Cup.
Pumas had Chile international Marcelo Diaz sent off in the 20th minute for arguing with the referee, but managed to equalize just before half-time through Jesus Gallardo, who drove into the America penalty area and finished.
Striker Nico Castillo was also shown a red card in the 70th for a challenge on Edson Alvarez.
Ibarguen's strike 10 minutes from the final whistle handed America the victory on the night. He curled a shot from outside the penalty area into the right corner of the goal.
Club Tijuana joined America in the semis later on Saturday, defeating Monterrey 2-1 in Estadio BBVA Bancomer and going through 3-2 on aggregate.
Miller Bolanos scored the opener in the fifth minute, with Juan Lucero netting the second from close range in the 23rd as Tijuana's counter-attacked last season's finalist with ruthless efficiency.
Dorlan Pabon closed the gap for Monterrey two minutes after half-time, but Tijuana defended well and secured what was a surprise passage to the semis. Xolos hadn't won an away game in Liga MX since Oct. 17.
In Sunday's quarterfinals, Tigres hold a 2-0 advantage over Santos Laguna, while Morelia and Toluca are tied at 2-2.