WASHINGTON (AP) Nationals starter Gio Gonzalez felt as though nothing he threw had anything behind it, and the New York Mets took advantage.

Gonzalez was roughed up for seven runs and 10 hits in five innings as Washington lost to the Mets 7-1 Monday night in the series opener between the top two teams in the NL East.

The left-hander's worst outing of the season came in his first time throwing to catcher Wilson Ramos since September, but Gonzalez (3-2) took the blame.

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''It was just unfortunate I was flat today,'' Gonzalez said. ''It was just one of those games. I take this one on me. He did everything right as part of calling the game. If I execute the pitches that I wanted, and I bring it down with more movement, different game.''

Instead, Gonzalez got rocked in the third inning after hitting leadoff man Curtis Granderson with a pitch. Gonzalez allowed a single to Juan Lagares, a three-run homer to David Wright, singles to Yoenis Cespedes, Neil Walker and Asdrubal Cabrera, and a sacrifice fly to Eric Campbell in a five-run inning.

A changeup down the middle to Wright cost Gonzalez, and the inning snowballed from there.

''It happens in a short period of time,'' Nationals manager Dusty Baker said. ''I think it was 10 pitches and they had five runs. It turns into like a feeding frenzy. They start first-ball hitting and they smell blood in the water.''

Cespedes and Walker hit back-to-back home runs in the fifth to break the game open. Gonzalez's ERA rose from 1.86 to 2.87.

Gonzalez credited the Mets for seizing their opportunities. There were enough, even for a team that learned earlier Monday that first baseman Lucas Duda will be out at least four to six weeks with a stress fracture in his lower back.

New York leads the NL with 63 home runs, three of which came against Gonzalez on Monday night.

''He made some mistakes,'' Wright said. ''Instead of missing them or fouling them back, we hit them. We hit them hard.''

At the plate, the Nationals got another strong performance from Daniel Murphy, who went 2 for 4 and continues to lead the NL with a .389 batting average. Ryan Zimmerman also went 2 for 4 and drove in Washington's only run.

NL MVP Bryce Harper went hitless for the second straight game and is batting .220 in his last 100 at-bats over 34 games.

''All you can do right now is give him some love,'' Baker said. ''Right now, the No. 1 thing that's not giving him love is his bat.''

The Nationals have been used to Gonzalez's pitching providing a boost. Instead, the Mets got seven efficient innings from Bartolo Colon (4-3), who allowed one run and five hits.

''Just great command of his stuff. Just in and out, up and down,'' New York manager Terry Collins said of Colon, who was bothered by a stiff back on the eve of his 43rd birthday. ''I'm not sure if he threw 10 off-speed pitches. Just took something off his fastball, made it sink a little more, threw it a little hard at times.''

Gonzalez wasn't close to matching that effort.

''Just left pitches up,'' he said. ''They saw the pitch up, and they were making contact.''

TRAINER'S ROOM

Mets: INF Wilmer Flores (hamstring) will begin his rehabilitation assignment Tuesday with Double-A Binghamton. Collins said he didn't know if Flores would come off the disabled list Friday when eligible.

Nationals: RHP Matt Belisle (calf strain) began his rehab assignment with Class A Potomac, allowing a hit and striking out one in one inning.

UP NEXT

Nationals RHP Stephen Strasburg (7-0, 2.80 ERA) faces struggling Mets RHP Matt Harvey (3-6, 5.77), who's looking to get back on track.