Franca Jara's second half goal saw Pachuca earn a small advantage at the expense of Monterrey with a 1-0 win at the Estadio Hidalgo in the first leg of their Liga MX final clash.
Edwin Cardona had an early sight of goal but there was an even better chance for Omar Gonzalez at the other end when Jonathan Orozco was forced to get down and push wide.
Orozco had to make a another great save to deny Franco Jara moments later as Pachuca threatened to take the lead before the break.
At halftime, though, Pachuca were forced to make their first change when Colombian defender Oscar Murillo was forced off through injury.