Thursday’s playoff ties were equally tense affairs and in both cases the home sides may feel that failing to get the win may prove costly in the weekend returns.
In the earlier kickoff, Pumas snatched an injury time equaliser having been second best for much of their clash with Pachuca.
The league’s top scorer, Enner Valencia blazed a first half penalty over the bar as Pumas failed to really get too much of a grip on the game.
With 20 minutes remaining, Abraham Carreno put Pachuca in front but with seconds remaining, Javier Cortés fired in the crucial leveller. The away goal could be huge when they meet again in Mexico City in just a few days.
Later, Tijuana welcomed Toluca to the Estadio Caliente and were also left to rue a series of missed chances. Toluca were easily one of the strongest sides in the regular season but they will be confident in the second leg, knowing that Los Xolos are one of the weakest sides on the road.