J.D. Martinez drove in three runs - including two in Houston's six-run sixth inning - to lead the Astros to an 8-2 rout of the visiting Pittsburgh Pirates on Tuesday.

After Houston tied the game in the fifth on a solo home run by Jose Altuve, the Astros took control an inning later.

Pinch-hitter Matt Downs started a string of five straight singles in the sixth with an RBI hit against Charlie Morton (9-8). Martinez singled in a pair of runs and Jimmy Paredes capped the outburst with an RBI double, his second hit of the inning.

Martinez added another RBI on an infield single in the seventh as Houston won its third straight game.

Pittsburgh's Andrew McCutchen hit a solo homer with two out in the ninth.

Henry Sosa (2-2) allowed one run, two hits and struck out seven in six innings.

Morton gave up four runs, six hits, four walks and struck out eight in 5 1/3 innings.