Laynce Nix of the Nationals is met by teamates after hitting a three-run home run against New York Mets. (Al Bello/GETTY IMAGES)

The second roar came from inside the Washington Nationals’ clubhouse, as the players chose procrastination over packing for home. They glued their eyes to the flat-screen televisions ringing the room, together, watching the Masters. When a putt lipped out, their collective shout — “Ooohhhhh!” — and the ensuing taunts and laughter could be heard down the hall.

The first roar was earlier, when Ivan Rodriguez stood on first base and raised his right fist into the air. He had delivered the most crucial play on a day packed with them, the go-ahead single that keyed the Nationals’ 7-3, 11-inning, series-clinching victory over the New York Mets before 35,157 at Citi Field. Inside the Nationals’ dugout, players stormed the top step, high-fived and hollered.

“The place went crazy,” first baseman Adam LaRoche said.

With Ryan Zimmerman sidelined by an abdominal strain that may linger, the Nationals won despite entering with the eighth inning with one hit and a 3-1 deficit. They used 18 players in their third extra-inning game this season and received contributions from almost all of them.

Laynce Nix followed Rodriguez’s go-ahead hit in the 11th with a titanic three-run homer. Jason Marquis struck out nine in six innings. Four relievers allowed one hit and one walk while whiffing eight in five scoreless innings. Even Jordan Zimmermann, Friday’s starting pitcher, moved the go-ahead run to second with a pinch-hit sacrifice bunt.

“It was kind of a textbook game,” Manager Jim Riggleman said.

The Nationals finished their first road trip of the season 3-3, and they’ll come home to Washington 4-5 for the season, even in the standings with the Mets and ahead of the Atlanta Braves. They won three of four games, two in extra innings, after dropping the first two.

“It shows a lot about this team and the direction we’re headed,” Marquis said. “We feel good about ourselves right now. We have that attitude that we have a chance to win every day, every time we step on the field.”

They won Sunday when, in the 11th inning, they finally converted on one of the scoring chances they created. Adam LaRoche led off with a single, bringing up the pitcher’s spot in the lineup. Riggleman did not want to use another player from his bench, already diminished by Zimmerman’s injury. He figured Zimmermann, his fastest starting pitcher, would be least likely to bunt into a double play. Zimmermann grabbed a bat and walked to the plate.

“I knew we were getting low on guys,” he said. “I thought maybe I would have to do it.”

Zimmermann dropped down a perfect bunt. As LaRoche ran to second, he tweaked the left side of his groin, an injury he first felt while checking his swing earlier in the game. Riggleman did not want LaRoche to risk hurting himself while scoring on a possible game-winning hit, so he sent catcher Wilson Ramos — his last available bench player — into the game as a pinch runner.

Mets reliever Blaine Boyer hit Danny Espinosa with a pitch, which brought Rodriguez to the plate. The Nationals had been squandering chances like this all day and all season. They were 1 for 9 with runners in scoring position through the first 10 innings, making their total for the season 12 for 77 (.156).

Rodriguez did not seem like the ideal candidate to snap that slump. He came into the game hitting .077, and had been ordered to sacrifice bunt in his previous at-bat. But he had also sparked the eighth-inning rally that tied the game with a double, and he had been tinkering with his approach.

“Right now, I just try to stay back on the ball and use my hands,” Rodriguez said. “That’s me. I’ve got quick hands.”

Rodriguez shot a one-hopper through the infield, just under second baseman Daniel Murphy’s glove. Ramos thundered around third, with coach Bo Porter windmilling him home. Lucas Duda’s throw sailed up the line, allowing Ramos to score.

When Nix blasted one of Boyer’s change-ups over the bullpens in right-center, the Nationals could finally relax.

Mets right-hander Chris Young steamrolled the Nationals most of the day, allowing one hit — a single by Michael Morse in the second — in seven innings. But once the bullpen gate swung open, the Nationals rallied for six runs. “We just started grinding out at-bats,” Riggleman said.

Ian Desmond and Rick Ankiel drove in runs in the eighth with a flared single and a groundball, and the Nationals’ bullpen would not surrender anything. Tyler Clippard, Drew Storen and Sean Burnett pitched four of the five relief innings. Together, they have a 0.44 ERA and 20 strikeouts in 201 / 3 innings. They’ve also given the Nationals the belief they can win any game they keep close until the late stages.

“This group of guys has a chance to be something real special,” LaRoche said. “You can see it here when guys show up. You can see it after a loss when everybody is patting each other on the back.”

Sunday afternoon, there was no consoling in the Nationals’ clubhouse. There was celebration and laugher and even one roar, the sound of a team that is starting to feel good about itself.