Houston won on the road for just the seventh time this season.
The game was deadlocked at 2-2 going into the eighth, but Martinez sent a two-out single to center that brought home Marwin Gonzalez from second with the go-ahead run.
Houston then added three runs in the ninth with Carlos Pena hitting a leadoff homer, Gonzalez driving in another score with a squeeze bunt and Brandon Barnes producing an RBI single.
Paul Clemens (3-2) worked 1 2/3 innings of one-hit relief to get the victory. The tiebreaking run was charged to Edgmer Escalona (1-2)