Fernando Martinez chipped in with a RBI and a run scored as the Astros took the rubber match of a three-game series.
Gonzalez (2-0) earned the victory, fanning six while allowing a run on two hits and a walk over five innings.
Reds starter Johnny Cueto (17-8) dropped a second straight decision for the first time since the all-star break, yielding four runs on nine hits and a walk over four frames.
Jay Bruce provided the only RBI for National League Central-leading Cincinnati, which lost for the fifth time in eight games.
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