GUADALAJARA, Mexico -- A first half penalty from Matias Alustiza settled Thursday's Clasico Tapatio, with Atlas running out 1-0 victors against Guadalajara city rival Chivas in the quarterfinal first leg of the Liga MX 2017 Clausura.
Atlas had the better of the first half, but Chivas took the initiative after the break, with home side Atlas dropping back seemingly wary of conceding an away goal in front of almost 50,000 fans in Estadio Jalisco.
Atlas are looking to win their first Liga MX title since 1951, while Chivas -- one of Mexico's most supported teams -- are without a Liga MX title in a decade.
The only goal came in the 30th minute, with Argentine Alustiza coolly slotting in the penalty, which Daniel Alvarez had won following a rash tackle from Chivas' Michael Perez.
Chivas' play suffered after center-back Jair Pereira was taken off in the 15th minuted with what looked like a hamstring injury.
The visitors thought they had equalized when Alan Pulido tapped in before half-time, but it was rightly ruled out for offside.
Both teams had half-chances in the second half, but neither goalkeeper was particularly troubled.
Chivas have now gone six games without a win in Liga MX play and haven't scored a goal from open play over that period.
The second and decisive leg takes places in Estadio Chivas on Sunday.
In Thursday's earlier quarterfinal first leg, eighth-seed Morelia defeated top seed Club Tijuana 1-0 in Estadio Morelos.
Miguel Sansores netted the only goal in the 10th minute, slotting home at the back post with a nice sliding effort from a Jefferson Cuero assist.
The result puts Morelia in pole position to advance, although the victory came at a cost, with 2017 Clausura top scorer Raul Ruidiaz coming off injured in the 38th minute.