Danny Espinosa hit a two-run homer while Bryce Harper homered and hit an RBI triple, as the Nationals took the rubber match of a three-game series against the Mets with a 5-2 victory.
Ryan Zimmerman went 2-for-4 with an RBI for NL East-leading Washington, which has won three of four heading into its three-game series against the second- place Braves.
Gio Gonzalez (16-6) battled through 5 2/3 innings, but allowed just one run on seven hits and two walks to reach win No. 16 -- the most for any Nationals pitcher since their relocation in 2005.
"This is definitely a team accomplishment," Gonzalez said. "I couldn't have done this without them. The bullpen has been our biggest key, and I said it since the beginning: These guys come and clean up our mess. They are constantly working hard for us.
"But the offense was unbelievable, and the defense has been incredible. We are playing Nationals baseball, and it has been fun watching."
Kelly Shoppach went 2-for-3 with a walk and an RBI for the Mets, whose starter, Jeremy Hefner (2-5), yielded five runs on eight hits over five innings.
New York went 2-for-21 with runners in scoring position in the series, including a 1-for-11 effort on Sunday that saw 10 runners stranded.
"You've got to get key hits," Mets manager Terry Collins said. "We sat here the entire first half [of the season] and talked about how many key hits we didn't get with two outs. We're not getting them, and that's a big difference."
Espinosa got the scoring started in the second with an opposite-field shot. Michael Morse led off the frame with a single.
Werth also began the next frame with a base hit and raced around to score when Harper one-hopped the wall in right and legged out a triple. Zimmerman then singled in front of Jason Bay in left for a 4-0 cushion.
Harper's 12th home run of the season -- a shot off the second-deck facade -- led off the fifth.
The Mets had plenty of opportunities to inch closer, but only got runs in the sixth and eighth on Bay's groundout and Shoppach's single, respectively.
Tyler Clippard hurled a 1-2-3 ninth to secure his 27th save of the season.
The game was delayed two hours, 26 minutes due to rain ... The Mets are 1-9-1 in their last 11 series ... Mets pinch-hitter Daniel Murphy was ejected after being called out on strikes in the eighth ... The Nationals are 11-4 against New York so far this season.