Bryce Harper drove in the go-ahead run as part of a six-run 10th inning to lead Washington in an 8-2 win over New York in the opener of a three-game set.
Harper also had a solo home run while Ryan Zimmerman added a three-run double in the 10th and Michael Morse followed with a two-run homer to help the Nationals win a third consecutive game. Tom Gorzelanny (3-2) got the win for getting the final two outs of the ninth and working a scoreless 10th inning.
David Wright and Ike Davis hit solo home runs for the Mets, who have lost four straight and 10 of 11.
Neither starter factored in the decision despite both pitching well. Jordan Zimmermann went six innings for Washington and gave up just one run on four hits with six strikeouts, while Chris Young gave up two runs on three hits with three walks and seven strikeouts over seven innings for the Mets.
The Nats took the lead and then some in the 10th. With Tim Byrdak (2-2) on the mound, Roger Bernadina led off with a single. Sandy Leon then hit a grounder back to the mound and Byrdak quickly went to second, but Ruben Tejada was unable to hold on to the ball and everyone was safe.
"I tried to make the jump and turn too fast," said Tejada. "They had a really good runner coming to second, but that's no excuse because I have to make those routine plays."
Pedro Beato then took the mound and Mark DeRosa laid down a bunt that was fielded by Beato and he got the force out at third. Steve Lombardozzi, though, then singled to load the bases and Harper drove in the go-ahead run with a single to right. Ryan Zimmerman then cleared the bases with a double to center and Morse followed with a shot over the wall in center for an 8-2 lead.
"I just wanted to make sure I didn't hit into a double play there," said Harper. "Got a good pitch to swing at and I was just trying to get it into the outfield."
The Mets were unable to get any across in the bottom portion.
The Nats struck quickly in the opening frame to take the lead as Lombardozzi led off with a single and came home when Harper drilled a full-count fastball over the right field wall for a 2-0 lead.
In the fourth, the Mets got a leadoff single from Tejada, but Jordany Valdespin quickly hit into a double play. Wright then hit his 15th homer of the year, a shot over the left-center wall, to make it a 2-1 game.
Jordan Zimmermann departed after the sixth inning and Drew Storen got the first out of the seventh, but Mike Gonzalez then came on and served up a first-pitch homer by Davis that went off the webbing on the right field foul pole to tie the game.
Before the game, the Nationals placed shortstop Ian Desmond on the 15-day DL, retroactive to July 22, with a left oblique strain and recalled outfielder Corey Brown from Triple-A Syracuse...The Nats have won seven of 10 from the Mets this season.