WASHINGTON (AP) -- Jordan Zimmermann couldn't slow down the struggles of the Washington Nationals.
One start after his worst outing this season, Zimmermann allowed five runs in 6 2-3 innings in an 11-0 loss to the New York Mets in the first game of Friday's day-night doubleheader.
"I felt like, you know, I pitched a lot better than what the stat line says," said Zimmerman (12-6, 3.19 ERA), who fell behind 3-0 after allowing two home runs to Daniel Murphy during Murphy's first two at-bats.
"And I've thrown those pitches to Murphy plenty of other times and gotten him to ground out to second. Today just wasn't my day."
Murphy went 4 for 5, added a pair of RBI singles and tied his career high for RBIs.
That was more than enough against the Nationals, who followed Thursday's 9-7 win over Pittsburgh with a return to their offensive struggles.
Washington went 0 for 4 with runners in scoring position, failed to advance a runner to second base after the third inning, and was shut out for the 10th time this season.
Bryce Harper, who hit a walk-off home run in Thursday's win, aggravated his knee injury making a lunging catch during Friday's first game and was left out of the lineup for the second game.
Washington has lost seven of eight since the All-Star break, all at home.
Juan Lagares had three hits and Ike Davis added a three-run homer for New York, which has won five of seven.
Jenrry Mejia (1-0) pitched seven innings, allowed seven hits, striking out seven and walking none in his season debut.
"Whenever you face somebody for the first time, picking up the arm slot, release point, what his pitches do and what he likes to do, it's a little tougher," said Nationals catcher Kurt Suzuki of Mejia, who had been on the disabled since March with shoulder inflammation.
"But we have no excuse. You tip your hat. He threw the ball really well."
Zimmermann, meanwhile, showed glimpses of why he has been the Nationals' wins leader this season, striking out eight, walking three and allowing six hits while throwing a career-high 118 pitches.
But he also allowed five or more earned runs in consecutive starts for the first time in two years, thanks in large part to a pair of sliders thrown to Murphy.
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 lined another offspeed offering on a full count into the Nationals bullpen for his eighth homer.
"The first one was right down the middle," said Zimmerman, who has lost three straight starts. "The second one was 3-2. I'm not going to throw it for a ball. I was right on the inside, and he's feeling good right now."
New York added two runs in the seventh. Lagares singled home Anthony Recker and stole second. Manager Davey Johnson lifted Zimmermann for Francisco Abad, who allowed Lagares to score on Murphy's single.
The Nationals managed only three singles in the final six innings, the last off Harper's bat in the eighth inning.
Johnson inserted Scott Hairston as a pinch runner for Harper. Johnson said he thought Harper aggravated his left knee injury.
The Mets made it a rout with a six-run ninth capped by Davis' homer off reliever Drew Storen.
Murphy has hit safely in 15 of his past 16 games.
NOTES: LF Eric Young Jr. was scratched from the Mets 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. ... It was Murphy's second career multi-homer game. His first was June 27, 2012, against the Cubs. ... Zimmermann's eight strikeouts gave him 500 for his career. ... Washington activated RHP Ryan Mattheus from the disabled list. The reliever missed 58 games with a fractured right hand.
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