Washington’s Adam LaRoche hits a two-run home run in the 11th inning to lift the Nationals over the Marlins, 5-3. (J Pat Carter/AP)

Adam LaRoche stepped into the batter’s box late Thursday night and stared out to the pitcher’s mound, his front foot askew, that stance that makes him look like a bystander who had simply wandered into the moment. He had not started well with the Washington Nationals, not by the numbers, anyway. But he felt good about his swing. He is a man who knows himself.

“I’m not necessarily here to replace anybody,” LaRoche said. “I’m not going to step outside my comfort zone and try to be something I’m not.”

From the moment he signed with the Nationals, LaRoche made clear he had not come to replace Adam Dunn, the beloved slugger who occupied first base before LaRoche arrived. With one swing, LaRoche gave the Nationals an 11-inning, 5-3 victory over the Florida Marlins, saved them from a sweep and maybe made Nationals fans forget a little of the sting that came after losing Dunn.

The Nationals dug an immediate two-run hole and did not produce a base runner until their 11th hitter, but a series of contributions lifted them to their second victory of the season.

Right fielder Jayson Werth hit the first home run of his Nationals tenure.

The bullpen gave up two hits in six innings while striking out eight Marlins, bouncing back after losing Wednesday’s lead.

Sean Burnett earned his second save in the 11th inning. Their offense — now 7 for 50 with runners in scoring position for the year — managed to churn out three runs against Josh Johnson, perhaps the best pitcher in the National League. The Nationals had lost two games they felt they should have won, and they stole one they could have lost.

“This team is built a little bit different than the teams of the past here,” Werth said. “We’ve got a bunch of guys that are here to win, play hard, play the game the right way. The lackadaisical style of baseball that may have been here in the past, I don’t foresee that happening.”

After the bullpen preserved the game — Tyler Clippard, Drew Storen, Todd Coffey and Burnett, in that order — LaRoche stepped to the plate in the 11th to end it. He walked to the plate 3 for 23 with the Nationals. An infamous slow starter, LaRoche knows when to worry and when not. This was a time, he knew, he didn’t need to change.

“I don’t know what I’m hitting,” LaRoche said. “It doesn’t feel bad at all. You end up fighting against yourself, and nothing good comes out of it. Been there, done that, don’t want to do it again.”

LaRoche hides his competitiveness, but it is there. “He doesn’t like to let Drake beat him,” LaRoche’s father, Dave LaRoche, said. Drake is LaRoche’s 9-year-old son.

He dug in against reliever Edward Mujica, and on the second pitch he saw, LaRoche unleashed his swing – “one of the smoothest in the game,” Burnett said earlier this year. He destroyed the ball, lifting high into the night and five rows deep in left field.

John Lannan began his start with near disaster, yielding a walk, a single and an RBI double by Hanley Ramirez to his first three batters. The beginning fit with Lannan’s history — a 9.00 ERA coming into Thursday night — at Sun Life Stadium. The Marlins scored twice in the first, and with Johnson on the mound for the Marlins the deficit spelled doom for the Nationals.

Johnson retired the first 10 batters he faced, striking out half of them, firing blistering fastballs and wicked sliders. After the first three innings, it felt a long night ahead for the Nationals.

And then, in the fourth, up came Werth. He smoked an 0-1, 96-mph fastball to right field and zipped around the bases as the ball ricocheted back into the field off . . . something. The throw rifled in from the outfield and Werth slid headfirst into third base.

Werth hadn’t seen the umpire in shallow right circling his index finger, calling the blast a home run. The ball had actually bounced off a railing behind the fence, which an umpire’s review would verify. Werth brushed off the front his uniform and jogged home. “That’d be a first,” he said.

It took him 19 at-bats and an unusual, dirty detour, but Werth had hit his first Nationals home run and produced his first RBI.

Lannan settled, not allowing another run until the sixth. The Nationals offense churned out a run in the fifth, taking advantage of two misplays by Ramirez, and took the lead when Zimmerman lined an RBI single to right in the sixth, scoring Desmond.

Afterward, players ate fast and packed for their next stop, a series with the New York Mets. Jay-Z’s “Empire State of Mind,” pumped through the clubhouse. Third base coach Bo Porter looked to Jerry Hairston and said, “This is probably my favorite song.”

The Nationals rolled out of the clubhouse, bound for the concrete jungle where dreams are made of, ready to reveal more, and maybe learn more, about themselves.

“It’s really early,” Werth said. “But I like the signs this team is showing.”