America off the mark with 5-1 rout
Midfielder Angel Reyna and Paraguay's Salvador Cabanas scored twice each with Argentine playmaker Daniel Montenegro notching America's third.
Jesus Palacios headed an equaliser for San Luis from a corner after 34 minutes but he was sent off just past the hour for a second booking, the team's second dismissal of the game.
The first was fellow midfielder Gonzalo Pineda who was shown a straight red in the 38th minute for hitting Reyna.
Montenegro then had a field day pulling the strings for America and being involved in two quick goals that virtually settled the match.
He laid on America's second for Cabanas in the 52nd minute, then exchanged a one-two with the Paraguayan before netting his team's third a minute later.
The victory should help America overcome their disappointment at failing to qualify for the Libertadores Cup from playoffs that took place during the mid-season recess.
Champions Monterrey, who won the Apertura title in December, also started out with a glut of goals, beating Ciudad Juarez 4-0 on Saturday.