Colombian Aviles Hurtado came off the bench and struck in the second minute of injury time as Pachuca defeated lowly Veracruz 1-0 on Saturday.
Unmarked substitute Hurtado headed the ball into the bottom corner of the net at the Estadio Miguel Hidalgo as Pachuca won for the first time in four outings.
At the Estadio Olimpico Universitario de Colima, three goals in the opening 16 minutes saw Pumas to a 4-2 win over sixth-placed Monterrey on Sunday.
Mexican striker Eduardo Herrera was the hero, netting twice for the home team against Monterrey, who are already assured of a place in the play-offs.
Pachuca (25 points, +2) and Pumas (24 points, +4) finished seventh and eighth respectively, replacing Santos Laguna (23 points, -1) and Leon (22 points, +2), who both failed to win over the weekend.
Laguna twice surrendered a lead, conceding in the 90th minute as Puebla earned a 3-3 draw.
Veteran Cuauhtemoc Blanco, 41, struck the equaliser having put Puebla on level terms just past the hour-mark.
Defending champions Leon, who were reduced to 10 men in the first half, lost 3-2 at Tijuana.
Chiapas - fifth in the standings - secured their spot in the play-offs thanks to a 2-1 victory over Queretaro.
In other results, leaders America's (31 points, +10) winless run extended to four games after they were beaten 2-1 by third-placed Atlas (31 points, +2).
Second-placed Tigres UANL (31 points, +8) were 2-1 winners over Toluca, who dropped to fourth.
Omar Bravo scored twice as Guadalajara edged basement side Morelia 2-1, while Universidad Guadalajara and Cruz Azul played out a 1-1 draw.
