Flushing, NY (SportsNetwork.com) - Ryan Zimmerman hit an RBI single in the first inning and the Washington Nationals held on to beat the New York Mets 1-0 on Sunday, winning their four-game series.

Doug Fister (2-1) improved to 5-0 in five career starts against the Mets after working into the seventh inning. He allowed five hits, no walks and struck out three.

The Nationals won three of the four games, including back-to-back 1-0 decisions, improving to 17-2 in their last 19 at Citi Field. They have won five of their last six overall on the heels of a six-game slide.

"Our pitching was fantastic the last two days and the first game we scored a bunch of runs," said Nationals manager Matt Williams. "It doesn't matter how we get it done as long as we get it done. It was nice to come in here against a first-place club and play well."

Dillon Gee (0-2) faced the Nationals for a 17th time in his career -- his most common opponent -- and took the loss after giving up six hits and five walks.

The Mets dropped to 3-7 since their 13-3 start this season.

"When you have a staff like they have, you know they're going to be close games," said Gee. "They happened to come out on the winning end these last two games but it's a long season and you have to keep grinding it out."

After Zimmerman drove in the only run with his hit in the first inning, he had a home run taken away leading off the fourth when Mets left fielder Michael Cuddyer leapt at the wall to catch it.

Gee had two strikeouts while pitching out of a jam in the fifth after giving up a double to Denard Span and single to Yunel Escobar to put runners at the corners with no outs.

He was pulled with the bases loaded and nobody out in the sixth inning after issuing walks to Ian Desmond and Jose Lobaton around Danny Espinosa's double off Cuddyer's glove in left field.

But Alex Torres came in to strike out Fister, Span and Escobar to get out of the jam.

The Mets had just four hits -- all singles -- before Kevin Plawecki hit a one- out double off the base of the left-field wall to chase Fister in the seventh inning. Tanner Roark got the last two outs to preserve the lead.

Pinch-hitter John Mayberry Jr. drew a leadoff walk in the bottom of the eighth for New York but was eventually stranded at second base.

Drew Storen threw a 1-2-3 ninth inning for his seventh save of the season.

Game Notes

Gee struck out five ... Fister has given up just three earned runs, 31 hits and three walks in 33 career innings against the Mets ... The Nationals host Miami on Monday to start a six-game homestand ... The Mets start a two-game series at home against Baltimore on Tuesday.