An Edgar Benitez goal separated the sides.
Houston isn't out of the tournament just yet, but needs kind results elsewhere on the last day of group play.
The game was decided by an Edgar Benitez goal in the 23rd minute. Benitez used his chest to push a cross through a pair of Dynamo defenders and put him clear on goal. Then it was just a matter of sweeping the ball pas Houston 'keeper Pat Onstad for the game's only goal.
Jose Francisco Torres entered the match in the 52nd minute to play against some of his country-mates.
With 12 points from five games, Pachuca leads Group A. Between the Mexican club and Houston lies Arabe Unido with 10 points, three more than the Dynamo. The final matches of the group stages will be played on Oct. 21.
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