Sentimental favourite Tijuana will take a 2-1 lead into the second leg of their Liga MX final with 10-time champions Toluca on Sunday.
Just a year after promotion to Mexico's top flight, Tijuana could complete a sensational couple of seasons with the first division title after two goals in the first leg.
Fidel Martinez and Paraguay international Pablo Aguilar scored for Tijuana either side of Edgar Benitez's strike for Toluca in the first half at the Estadio Caliente.
Aguilar reacted quickest at the far post from a set piece to prod home shortly before half-time, restoring Tijuana's lead to the delight of a raucous home crowd.
In a free-flowing second-half, both sides had chances to score but it was Toluca who will feel the most aggrieved after a late penalty appeal was waved away.
Toluca, who have won seven league titles since 1998, can match Guadalajara Chivas' record of 11 if they can turn the tie around in the second leg.