Leandro Barrera almost handed the home side the lead when he cut in from the right and beat two defenders. The winger then unleashed a shot at goal that Troy Perkins could only parry, but Heath Pearce was on hand to clear the danger.
Chivas threatened again down the right before half time as Marvin Chavez beat his man and found space to curl a shot at goal, only to see his effort go just the wrong side of the post.
The home side responded and Eric Avila's shot from distance forced Perkins into another stop as the keeper had to tip his deflected effort over the bar.
Chivas kept pushing for a winner late in the game and they got their reward in stoppage time when Marco Delgado's shot was deflected into the path of Torres, who acrobatically fired a volley into the top corner.