WASHINGTON (AP) -- The Washington Nationals have had trouble winning games since the All-Star Break.
When they have come out on top, it's been dramatic.
Ryan Zimmerman homered with one out in the bottom of the ninth inning Friday night, lifting the Nationals to a 2-1 victory over the New York Mets for a doubleheader split.
''Just worked into a good count and finally didn't try to do too much,'' Zimmerman said. ''Good win. I mean obviously with Harvey starting it's tough to get any runs, but (Ross) Ohlendorf stuck there right with him, and after the way that first game went, that was a huge win.''
After Washington's second walk-off win in two days, struggling setup man Drew Storen was sent down to Triple-A Syracuse. The Nationals improved to 2-7 since the break.
In the opener, Jenrry Mejia pitched seven scoreless innings in his season debut and Daniel Murphy homered twice and tied a career high with five RBIs as Mets won 11-0. Murphy had two hits for New York in the nightcap and went 6 for 9 in the day-night doubleheader.
After Anthony Rendon grounded out, Zimmerman hit a 3-1 fastball from reliever LaTroy Hawkins (3-2) over the fence in right center for his 12th homer of the year. The Mets wasted another impressive outing by Matt Harvey, who gave up five hits and an unearned run in eight innings.
Rafael Soriano (2-2) pitched the ninth, surviving a first and third jam with one out.
Jayson Werth added three hits for Washington.
Manager Davey Johnson announced Storen's demotion.
''There's (been) a lot of discussion about it, even before now, that maybe, he's never had failure, he's never had to deal with failure, and this is kind of a sharp lesson in dealing with failure,'' Johnson said of Storen. ''I mean, we could've done different things with different players, but I think it's going to be best served for him to get it right and get it back.''
Storen is 3-2 with two saves and a 5.95 ERA.
The Nationals activated reliever Ryan Mattheus from the disabled list Friday as the 26th man for the doubleheader.
Storen entered the ninth inning of Game Five of the NL Divisional Playoff series in October with a two-run lead and gave up four runs as the St. Louis Cardinals ended Washington's season. In the offseason, the Nationals singed free-agent closer Rafael Soriano.
''I think there's a lot of things that led to this that could've been prevented,'' reliever Tyler Clippard, Storen's close friend, said. ''You know, you basically send a guy a message this offseason for having one bad game that he's not the guy for the job. He's only human. It's going to get to anybody.''
Storen was unavailable after the game.
''It's one of those things that I think was handled very poorly by the organization, but at the same time, that's the decision that was made, and we have to move forward as a team,'' Clippard said. ''We have great guys in this locker room that are going to get it done, we're going to make a playoff push at the end of the season. I have no doubt about that, but you know, this is a tough day.''
Pitching on the one-year anniversary his major league debut, Harvey struck out seven and walked one. He left after throwing 99 pitches.
''I was locating everything pretty well,'' Harvey said. ''The fastball command was right on point. I was keeping everything down.''
Washington starter Ross Ohlendorf, making his second start of the season, went seven innings. He allowed one run on six hits while striking out eight and walking two.
With one out in the fourth New York's Josh Satin doubled. Ohlendorf fanned Justin Turner, but John Buck doubled to the wall in left to make it 1-0.
The Nationals tied it in the fifth. Werth led off with a single and Ian Desmond walked. After Harvey fanned Steve Lombardozzi, Wilson Ramos hit a grounder up the middle. Turner fielded the ball behind second and shoveled it with his glove to Murphy.
Murphy barehanded it for the force and turned and threw to first, but his throw was wide and hit Ramos, allowing Werth to score on the error as the ball rolled into the infield.
''I misplayed the only ball that really mattered all night,'' Murphy said.
In the opener, Murphy went 4 for 5 with two homers and a pair of RBI singles. Juan Lagares had three hits and Ike Davis added a three-run homer for New York.
Mejia (1-0), who had been on the disabled list since March with shoulder inflammation, allowed seven hits. He struck out seven with no walks.
Mejia, 23, was 0-4 for the Mets in 2010. He underwent Tommy John surgery in 2011 and spent most of 2012 at Triple-A Buffalo. He was 1-2 with a 6.33 ERA in three September starts for the Mets.
Prior to being recalled for Friday's start, the right-hander went 2-0 in a pair of rehab starts at Double-A Binghamton.
Jordan Zimmermann (12-6) needed 118 pitches to go 6 2-3 innings. He allowed five earned runs and six hits in picking up his third straight loss.
With one out in the first, Murphy hit a 1-1 slider off the second deck facade in right-center to make it 1-0.
In the third, after Lagares doubled with two outs, Murphy put New York up 3-0 when he lined a pitch into the Nationals bullpen for his eighth homer.
Murphy has hit safely in 16 of his past 17 games.
After Washington's Bryce Harper singled in the eighth, he was removed for pinch-runner Scott Hairston and was not in the lineup for the second game. Johnson said Harper aggravated his left knee diving for a ball.
Harper pinch hit in the second game and grounded out.
NOTES: Mets LF Andrew Brown and SS Justin Turner collided and appeared to bump heads while chasing a popup in the first inning of Game 2. Turner made the catch and remained down as the Mets' trainer came out. Turner and Brown remained in the game, but Turner left in the seventh with a sore right shoulder. . LF Eric Young Jr. was scratched from the Mets game one lineup after a pregame workout to test his right knee. He injured the knee Wednesday on the play in which Tim Hudson fractured his right ankle and left Thursday's game against Atlanta in the fourth inning. ... New York's Dillon Gee (7-7, 4.07) opposes Dan Haren (4-11, 5.79) Saturday.