HOUSTON -- Adam LaRoche hit a tying double in the eighth inning and a go-ahead single in the ninth Tuesday night that lifted the Washington Nationals over the Houston Astros 4-3.
Jayson Werth homered as the Nationals won the opener of the interleague series.
Denard Span drew a leadoff walk in the ninth, stole second base and advanced to third on a groundout. He scored on LaRoche's hit to right field off Josh Fields (0-3).
Tyler Clippard (2-2) pitched a scoreless eighth for the win. Rafael Soriano walked two in a scoreless ninth for his fifth save.
Werth connected in the first for his fourth home run. Houston scored three times in the third for a 3-2 lead, helped by rookie George Springer's two-run single.
Werth singled to start the eighth and scored on LaRoche's double to left-center field. Center fielder Dexter Fowler tracked the ball to the wall, but it glanced off his glove as he crashed to the ground.
The Nationals went on to load the bases before Chad Qualls struck out Jose Lobaton.
Washington starter Gio Gonzalez allowed five hits and three runs, striking out a season-high nine in six innings.
Houston's Jarred Cosart gave up five hits, a pair of runs and fanned six in six innings in his first career start against an NL team.
Cosart plunked Kevin Frandsen to start the third inning and he scored on a double by Lobaton to make it 2-0.
Houston's first hit came on a double by Matt Dominguez to open the third and he moved up on a sacrifice bunt by Jonathan Villar.
Fowler's two-out single cut Washington's lead to 2-1 and extended his hitting streak to nine games. Jason Castro doubled on a ball that bounced off the padding on the wall in left field -- Frandsen saved a run when he made a nifty no-look, backhanded stop on the carom.
Springer's single on a line drive to left field put Houston ahead.
The Nationals had another good defensive play when Span ran up Tal's Hill in center field and landed on his backside as he caught a fly ball hit by Dominguez for the second out of the fourth inning.
NOTES: These teams wrap up the two-game series on Wednesday when Houston LHP Brett Oberholtzer opposes RHP Jordan Zimmermann. ... Washington OF Bryce Harper had surgery on his injured left thumb on Tuesday and will be out for an extended period of time. Harper was injured on Friday night against San Diego on a headfirst slide into third base on a triple. ... Houston RHP Scott Feldman, on the 15-day disabled list retroactive to April 18 with right biceps tendinitis, said he felt good after throwing 35 pitches in a bullpen session on Tuesday. He is eligible to come off the disabled list on May 3.