The Mets’ Ike Davis tosses his bat after striking out in the first inning at Nats Park. (Alex Brandon/Associated Press)

Jordan Zimmermann scythed through the opposing lineup Wednesday night without help from his offense, the defining story line of his career. But by now in the Washington Nationals’ enchanted season, especially when they play at Nationals Park, the proper ending has become an expectation. Somehow, the Nationals will figure out a way to score some runs, hold the lead and send everyone home happy, ready to come back and watch another ace the next day.

As Zimmermann extended his recent dominance with six scoreless innings, the Nationals supported him just enough and beat the New York Mets, 4-3, to keep their grip on the National League East. Closer Tyler Clippard made it dicey in the ninth, but the Nationals moved eight games ahead of the third-place Mets and now lead the Atlanta Braves by 41 / 2 games.

Adam LaRoche drilled a two-run homer, his 16th, that secured Zimmermann’s seventh win. Steve Lombardozzi added a clutch, two-RBI double off the top of the right field wall in the seventh inning, turning a 2-1 nail-biter into a three-run breeze. The runs changed the game more than the Nationals would have hoped.

Clippard, on the day before Drew Storen’s expected return, suffered another hiccup when he surrendered a solo homer by David Wright to lead off the ninth inning. With two outs, he gave up another to Jason Bay, crushed off the left field foul pole. He rebounded to retire Jordany Valdespin, who rocked a homer off him during his Tuesday meltdown, to seal his 15th — and shakiest — save.

“That was almost as fun as last night,” Manager Davey Johnson said.

The night, again, belonged to Zimmermann. He has opened the second half of the season with 12 consecutive scoreless innings. He has allowed one or no runs in five straight starts, a streak that lowered his ERA to 2.35, best among Nationals starters — better than all-stars Stephen Strasburg and Gio Gonzalez, Thursday’s starter — by nearly a third of a run. For most of this season, the Nationals may have thought they had two aces. Now they know they have three.

“He’s a man out there,” Johnson said. “He has a great presence. He knows what he wants to do. There’s no muss, no fuss. Here, hit it.”

The victory nudged the Nationals to 17 games over .500, a new high-water mark for the season. They have taken hold of Washington, vaulting from also-ran to NL pacesetter. They are young and may well contend for years to come, but there will never be another year like this one, when they took baseball by storm and the city by giddy surprise.

Stories spill out of these Nationals. After the flap this weekend in Miami between Marlins Manager Ozzie Guillen and Nationals rookie Bryce Harper, LaRoche sent Guillen a bat autographed by Harper. “I covered that thing in pine tar,” LaRoche said. It turns out LaRoche once served as Guillen’s batboy, when LaRoche’s father coached for the Chicago White Sox.

“This is part of this team’s progression right now,” said outfielder Jayson Werth, who will begin a rehab assignment Friday. “We’re building relationships and chemistry that could go on for the rest of our lives. This is a fun time. This is what it’s all about right here. Hopefully you build on this year. You become a better team. The more you play with each other, the more you learn each other. That’s when it gets fun.”

Zimmermann began Wednesday having thrown 68 percent of his pitches for strikes, third in the majors behind only R.A. Dickey and Cliff Lee. He continued his assault on the strike zone. Zimmermann walked none and reached a three-ball count only three times. He controlled both his sharp slider and his looping curveball.

“When I got those two, it’s a lot of fun going out there to pitch,” Zimmermann said.

Zimmermann’s most crucial work came in his final inning. The game remained scoreless into the sixth, Chris Young’s sinker rolling over the Nationals. Young himself led off the sixth with a double to left field. Zimmermann would face the top of the Mets’ order, starting with Ruben Tejada, a .324 hitter. Even a groundball to the right side, pushing Young to third with one out, would change the game.

“I had to get him out and keep Young at second anyway I could,” Zimmermann said.

Zimmermann tried to jam Tejada and force weak contract to the left side. Tejada fought to a 3-2 count. Zimmermann stared in for the sign, and then stepped off, still pondering. As he peered in again, catcher Jesus Flores called timeout and jogged to the mound. “We better challenge this guy,” Flores said. “I think you can get him with a fastball.” Zimmermann agreed.

“We went with the heater,” Zimmermann said. “We weren’t going to mess around, try to be cute with a slider and end up walking him, really have our hands full.”

Zimmermann pumped it into the strike zone, 93 mph, and Tejada popped up to foul territory in right field. Michael Morse tracked the ball down, shallow enough to hold Young.

Daniel Murphy grounded a curveball to second, which left the inning to Wright, who had two hits in his first two at-bats. Wright pummeled a 1-1 fastball to right-center field but Harper, sprinting on contact, snagged the line drive on the run.

“I was cheating a little bit with my step,” Harper said. “I felt good all night. This crowd pumps me up when I’m back here.”

For the 19th time in 19 starts, Zimmermann had pitched at least six innings. Nothing but zeroes on the scoreboard, he faced the prospect of another hard-luck no-decision.

With one out in the bottom of the inning, Harper bounced a chopper up the middle and ran hellbent for first. Tejada fielded the ball moving across second base, and his momentary bobble sealed Harper’s single.

With two outs, LaRoche came to the plate. He had blasted three balls to the warning track in the Nationals’ previous series at Marlins Park, the kind of oversize park that makes hitters go home and kick the dog. Against Young, on a 1-2 slider, LaRoche let loose his easy swing. The ball rocketed off his bat and landed in the red seats. The home run put the Nationals ahead, 2-0, and Zimmermann in position for the win.

“I’ll buy him whatever he wants, I guess,” Zimmermann said. “A steak or something.”

Said LaRoche: “We’ve been rough on him. He did what he’s been doing all year. He worked quick, lot of strikes. He’s a battler out there.”

LaRoche paused, and a thin smile creased his face, one more story about to come.

“I’ll take him up on that steak, though.”