The Houston Astros made several moves to improve their bullpen this offseason after it blew a MLB-leading 29 saves last year.
So far the revamped group hasn't helped the Astros hold leads any better than it did in 2013.
Adam LaRoche hit a tying double in the eighth inning and a go-ahead single in the ninth Tuesday night to lift the Washington Nationals over the Astros 4-3.
It was the sixth time this season Houston has blown a save.
"It's very concerning, because our starting pitcher did a very good job," manager Bo Porter said. "You feel like you are in position to win the game, you have the right guys matched up, and you just don't get it done."
Jayson Werth homered as the Nationals won the opener of the interleague series.
Denard Span drew a leadoff walk in the ninth, stole second and advanced to third on a groundout. He scored on LaRoche's hit to right field off Josh Fields (0-3).
Fields threw six straight balls when he entered the game before managing a strike.
"It was just command," Porter said. "If you look at the walks that is pretty much what hurt us. There's no defense for walks. You don't get a chance to defend the baseball."
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 and two 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.
"That was a big spot in the game, and I was just happy to drive him in and get a lead for (Cosart)," Springer said. "He really threw a great game, and we're all out there trying to get him the win. I am just out there trying to help us win right now."
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 Friday night against San Diego on a headfirst slide into third base on a triple. ... Houston RHP Scott Feldman, on the 15-day DL 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 DL on May 3.