It's advantage Club America in the Liga MX Clausura semifinal against Monterrey, after Las Aguilas defeated Los Rayados 1-0 in the first leg on Wednesday in Estadio Azteca.
Paraguayan Osvaldo Martinez netted the winner just after halftime to put fourth seed America in the driving seat against regular season leader Monterrey in the two-leg series.
America goalkeeper Hugo Gonzalez and Monterrey stopper Jonathan Orozco kept the score-line down in what was an entertaining game with a total of 36 shots (18 or America, 18 for Monterrey).
Monterrey had the better of the chances in an even first half, with Uruguay international Carlos Sanchez forcing Gonzalez into a reflex save in the 11th minute.
U.S. International Edgar Castillo burst down the left wing, exchanged passes with Rogelio Funes Mori and shot on the volley 10 minutes later, but Gonzalez was well placed to make the save.
A diving header from America's Pablo Aguilar forced a save Orozco in the 33rd as the game swung back and forth.
Right after halftime, Martinez controlled and finished first time from an Andres Andrade cross, with Monterrey defender Efrain Juarez slipping to leave him free inside the penalty area.
Las Aguilas came close to doubling the lead in the 70th when Paolo Goltz headed onto the crossbar from a corner.
The game opened up more as Monterrey chased an equalizer, with Colombian Edwin Cardona skipping past two America defenders and forcing yet another save from Gonzalez in the 79th.
The return leg takes place in Estadio BBVA Bancomer in Monterrey on Saturday, with away goals counting. If the aggregate score is level and away goals are the same, Monterrey would advance due to its higher finishing position in the regular season.
The other semifinal final first leg will be played on Thursday in Estadio Leon between Leon and Pachuca, with the second leg in Pachuca on Sunday.