Now they have every reason to think they're in a tight race to the finish.
Jordan Zimmermann gave up three home runs in a span of five pitches, a sudden power strike that sent the Mets past Washington 5-2 Sunday night for a three-game sweep.
"Tonight was one of those nights when I made two mistakes and it looks a lot worse than it was," Zimmermann said.
Curtis Granderson, Daniel Murphy and streaking Lucas Duda went deep against Zimmermann in the third. Noah Syndergaard (6-5) struck out nine over eight innings, and New York pulled within percentage points of the first-place Nationals.
Boosted by a trio of lively crowds, the Mets completed their first three-game sweep of Washington since May 2009 and boldly pronounced themselves legitimate contenders.
"We saw all three of their horses twice in the matter of two weeks," Bryce Harper said. "They haven't seen (Max) Scherzer since Day 1. We still have (Stephen Strasburg) coming back. The Mets are a great team. It's definitely going to be a lot of fun down the stretch."
It was indeed a serious statement from the rising Mets, now 7-6 against the Nationals this season after going 4-15 last year.
Coming into the series, the Nationals had won 18 of their last 21 at Citi Field. The teams meet six more times this year, Sept. 7-9 at Washington and Oct. 2-4 in New York during the final series of the regular season.
"The crowd was a little more into it," Nationals infielder Anthony Rendon said. "Last year the atmosphere was a little different."
Rendon hit his first homer this season on Syndergaard's fifth pitch, and Yunel Escobar also went deep for Washington.
Normally a Mets nemesis, Zimmermann (8-7) issued a leadoff walk in the third. Two outs later, Granderson launched a 2-2 curve into the front row of the second deck in right field.
Murphy hit the next pitch almost halfway up those bleachers, a little to the right of Granderson's drive. Yoenis Cespedes then singled for his first hit with the Mets, and by the time Duda plunked the facing of the second deck with his 21st homer, the chanting crowd of 35,374 was in a full-out frenzy.
"I'm not really sure how it's physically possible to hit that ball where I put it," Zimmermann said. "It was up and in for a ball up, and somehow he kept it fair."
It was Duda's ninth home run in his last eight games. He homered twice Saturday night and hit a tiebreaking double in the eighth inning of a 3-2 win.
"He's probably the hottest guy in baseball right now," Zimmermann said.
It also marked the first time the Mets, the lowest-scoring team in the majors this season, hit three long balls in one inning since June 7, 2007, when Carlos Delgado, David Wright and Paul Lo Duca connected in succession off Philadelphia lefty Cole Hamels.
Syndergaard, who carried a perfect game through six innings during his previous start against the Padres, walked none and scattered seven hits. The 22-year-old rookie fanned Harper with his 109th and final pitch, a 99 mph fastball.
Tyler Clippard, who spent seven years with the Nationals, got three outs for his first save with the Mets. He had 17 for Oakland this season before getting traded last Monday.
"I've never been in a playoff atmosphere, but tonight sure felt like one," Duda said.
Zimmermann was 5-0 with a 2.70 ERA in his previous seven starts against the Mets, all Washington wins. He had won three straight at Citi Field with a 1.50 ERA, throwing 13 consecutive innings without allowing an earned run. It was the first time he yielded three homers in a game since Aug. 19, 2013, at the Chicago Cubs.
Nationals: The team hopes Strasburg (left oblique strain) can return to the rotation after one more rehab outing Monday for Triple-A Syracuse. He is expected to throw 80-85 pitches.
Mets: LF Michael Cuddyer (left knee inflammation) headed to Florida to begin baseball activities at the team's complex in Port St. Lucie. ... OF Kirk Nieuwenhuis was placed on the 15-day disabled list with discomfort in his neck and left shoulder. Prized outfield prospect Michael Conforto was recalled after a one-day assignment to Triple-A Las Vegas — he never even left New York.