Nationals 4, Astros 3: Gio Gonzalez tossed his second career complete game and hit his first home run as visiting Washington won its fifth straight.

Gonzalez (14-6) struck out seven and walked two while being charged with three runs on nine hits to pick up the win. The left-hander doubled his career RBI total in the second, when he came up with Kurt Suzuki on first base and ripped a first-pitch fastball from Armando Galarraga deep into the Crawford boxes in left field.

Ryan Zimmerman recorded a pair of hits and scored a run for the Nationals, who maintained a four-game lead over the Atlanta Braves in the National League East.

Washington and Houston traded runs in the first inning, with rookie Bryce Harper scoring on Galarraga’s balk in the top of the frame and Justin Maxwell evening the score with an RBI single in the bottom.

Gonzalez’s blast made it a 3-1 gap until the Astros cut the deficit in half on Carlos Corporan’s sacrifice fly in the fourth.

Gonzalez was stingy from there until the ninth, when the Astros rallied for a run and put runners on second and third before Gonzalez finished it off.

Galarraga (0-2) struggled with his command in five innings, issuing six walks and getting charged with three runs on six hits. The right-hander has walked 13 in 10 1/3 innings over his last two starts.

The Nationals tacked on an insurance run when Zimmerman crossed thanks to an error in the seventh. That became important in the bottom of the ninth, when Ben Francisco singled in a run.

GAME NOTEBOOK: Nationals OF Jayson Werth (leg soreness) returned to the lineup and went 1-for-4 with a walk. … Gonzalez is the third Nationals pitcher to homer this season after Stephen Strasburg and Jordan Zimmermann. … Washington clinched its first series win in Houston since 2007. … Astros rookie OF Brandon Barnes recorded his first career hit with a single in the ninth. … Nationals OF Michael Morse went 1-for-5 to extend his hitting streak to 17 games.