With the bases loaded, Nationals left fielder Laynce Nix lays all out to catch a ball hit by the Phillies’ Domonic Brown for the final out of the sixth inning. (John McDonnell/The Washington Post)

John Lannan stood in the dugout, hair slicked back with a splash of cold water, and hoped. The bases were loaded, there were two outs in the sixth inning and the Washington Nationals led by a run. Their chance for a season-altering victory and a win Lannan had waited for since his first day in the majors hung in the balance. Standing in left field, Laynce Nix had a hunch.

The line drive hissed through the afternoon haze at Nationals Park, toward the gap in left-center. Lannan watched, the weary viewer who knows how the movie is going to end — so this was how he would lose to the Philadelphia Phillies.

Lannan said later: “As that ball was going, it was like it was in slow motion.”

Wednesday was different. From the left of the frame, from nowhere, Nix emerged and made a diving catch, the capstone to the Nationals’ 2-1, series-clinching victory over the Phillies. Before 24,495, Lannan allowed his nemesis one run, none earned, in 5 1 / 3 sweltering innings. He yielded four hits and three walks, striking out one and, in his 14th career start against the Phillies, earned his first win against them. Wile E. Coyote caught the Road Runner.

Lannan’s milestone win gave the Nationals their third series victory over the Phillies since the start of 2008, a span of 21 series. The Nationals limped off the field Monday having lost 10 of 12 overall and six straight against the Phillies. Then they beat Cliff Lee and Roy Oswalt on consecutive days, salvaging a 3-3 homestand and, maybe, sending a message.

“Anytime you win a series, especially against a first-place team, it’s a big win,” former Phillie Jayson Werth said. “To lose a series to a team in last place in your division, outside, formerly inside, looking in, that’s a tough loss. That’s a lot to swallow. Hopefully that will catapult us and send them reeling.”

Afterward, Lannan insisted he hardly ever thought about the Phillies’ hex on him. “Some of my buddies are up in Philly,” he said. “And they gave me a hard time about it.”

Lannan may have blocked it from his mind, but his difficulty against the Phillies helped shape his career. He walked to the mound 0-10 with a 6.44 ERA against them. He had an overall 4.13 career ERA, but if you removed his starts against the Phillies, it would’ve been 3.86. Lannan made his debut against the Phillies and was ejected after he broke Chase Utley’s hand with a pitch. The Nationals beat the Phillies that day. They had lost all 12 games Lannan had started against them since.

“I thought we were going to score some runs on him, if you want to know the truth,” Phillies Manager Charlie Manuel said.

When Manager Jim Riggleman scribbled his lineup card Wednesday morning, he mistakenly wrote “LANNEN” in the pitcher’s spot. And Lannan, coming off a start in which he allowed no runs in 7 2 / 3 innings, was a different pitcher. He pitched aggressively, pounding left-handers with sinkers for inside strikes, mixing in change-ups away and slow curves.

The only run Lannan gave up came in the second inning, after Alex Cora booted a one-hopper off of Carlos Ruiz’s bat. The possible double-play ball scored Ryan Howard and set up potential disaster, with runners on first and second and one out, the kind of situation that so often snowballed for Lannan against the Phillies. Wednesday, he squirmed out of trouble with a flyball to center and a grounder up the middle.

“I limited the damage,” Lannan said. “That’s all you got to do sometimes.”

Lannan did not allow another run, which made Werth’s RBI single in the first and Nix’s solo homer off Oswalt in the third stand up. Lannan exited in the sixth, with one out runners on first and second.

Todd Coffey relieved him and induced a flyball, then pitched around pinch-hitter Jimmy Rollins to load the bases. Manuel sent Domonic Brown to pinch-hit for Oswalt, and Riggleman countered with lefty Doug Slaten from the bullpen.

In left field, Nix expected a hit to his left. The way Brown swung, and with a lefty-lefty matchup, he could envision that kind of play.

“Right after a pitching change, it’s easy to sort of get on your heels, not be ready,” Nix said. “It’s important to be alert. Sometimes, if you play the game a long time, you get a gut feeling on things.”

On Slaten’s second pitch, Brown smoked a liner toward the gap. “I thought there’s no way that ball’s being caught,” Riggleman said.

Nix had a perfect jump. He charged across the outfield, closing in as the ball sliced and dropped — “that was a hell of a lot of ground really fast,” Slaten said. Nix slid on his chest, still unsure if he would catch the ball when he left his feet. As he skimmed across the turf, his arm fully extended, the ball settled into his glove. He knew he caught it when he heard the crowd.

“It would be easy for that ball to go off your glove,” Nix said. “It’s just concentrating that extra split-second. It was a good feeling.”

From there, the Phillies never threatened. Tyler Clippard retired all six batters he faced. Drew Storen slammed the door in the ninth, striking out Placido Polanco to end it with Rollins on first.

The Nationals had secured a rare series win against the Phillies, a precious achievement with an 11-game, Western swing looming. They did it with Lannan securing his first win.

“I’ve never pitched well against them,” Lannan said. “And today was just different.”