Matt Kemp is out at home after trying to score on Carl Crawford’s fourth-inning bunt Tuesday in L.A. (Mark J. Terrill/Associated Press)

Clayton Kershaw tortured the Washington Nationals in all the expected ways Tuesday night. Hitters tried to ignore the sight of his delivery coming at them, the knee-to-chin leg kick giving way to his funky-quick motion, a delivery that spit out a combination of sadistic curveballs and sudden fastballs. For eight innings, one swing from Bryce Harper aside, Kershaw lived up to his best-pitcher-in-baseball billing.

But Kershaw managed to tip his duel with Doug Fister in an unexpected way. Kershaw created the crucial rally in the Nationals’ 4-1 loss to the Los Angeles Dodgers not from the Dodger Stadium mound, but on the base paths. Kershaw’s bold base running decision, testing Harper’s arm in center field by going first to third, sparked Fister’s undoing in the fifth inning and turned a toe-to-toe pitching matchup into a knockout.

Fister stood toe-to-toe with Kershaw for four innings, but the Dodgers scored two runs off him in the fifth, only one earned, and another two in the sixth. The Nationals needed to play perfect behind Fister to give themselves a proper chance against Kershaw. They were far from it. They mangled plays and misfired throws, the most jarring by shortstop Ian Desmond.

“That’s the thing about Kershaw — to beat him, he makes you play a flawless game,” Manager Matt Williams said. “Tonight was kind of a clunker.”

Fister pitched well until the sixth, but he still continued his recent downswing. After winning 14 of 17 times Fister took the mound, the Nationals have lost his past three starts. Fister has allowed 27 hits in those 16 2 / 3 innings. Five have been home runs. Many have been cheap bloops. Fister believes he’s responsible for both.

Dee Gordon and his starting pitcher Clayton Kershaw share a moment at the plate after scoring on Adrian Gonzalez’s fifth-inning single. (Mark J. Terrill/Associated Press)

“I got to be better,” Fister said. “I can get it in, but I need to get it further in. They can’t get bloop hits. They can’t squeak ones up the middle like that. It’s something I got to be better at. I got to be better at picking up teammates. That’s unacceptable for me. That’s what good teams do, and I didn’t do that.”

Kershaw allowed three hits and walked two in eight innings, choking the life out of the Nationals’ lineup. Wilson Ramos and Anthony Rendon singled, and Harper provided the Nationals’ only run with a mammoth homer on Kershaw’s first-pitch fastball in the seventh inning, a lightning bolt that drove home a startling point: Harper was the first left-handed batter to drive in a run against Kershaw all season.

“He’s the best pitcher in baseball, hands down,” Harper said. “He goes out there every single night. He locates his pitches — he has his fastball, his curveball, his change-up, slider. He’s very, very good. He’s definitely the best pitcher in baseball, I think.”

Harper cherished the homer, but he also tipped his cap to Kershaw. “The second AB, he made me look pretty dumb with a curveball — probably the best curveball I’ve ever seen in my life,” Harper said.

The Nationals need a victory Wednesday afternoon to salvage a 4-5 road trip, but they have maintained a stranglehold on the National League East. The Atlanta Braves lost at home to Phillies, keeping the Nationals’ lead at seven games and reducing their magic number to 18.

The Nationals’ downfall began in the bottom of the fifth. With one out, Kershaw lined a single into center, which gave him the same number of hits recorded as allowed.

Dee Gordon followed with a soft liner into center field, and as Harper charged the ball, Kershaw decided he would go first to third. Harper fired a bullet, but it pulled Rendon off third base.

The Post Sports Live crew debates where Matt Williams should play Ryan Zimmerman when he returns from the DL to a likely first-place team in the middle of a pennant chase. (Post Sports Live/The Washington Post)

“I thought I made a pretty good throw,” Harper said. “I just didn’t get it on the dot. He didn’t surprise me at all. He’s pretty aggressive. He swings the bat every time he’s up there. He’s a heck of an athlete.”

Rendon made a rapid calculation: he thought had a better chance throwing to second for Gordon than trying to tag Kershaw. As Kershaw slid into third, Rendon whipped the ball to second, but it arrived too late.

“I was on the left side of the bag,” Rendon said. “I knew that he slid inside. So I saw Dee Gordon about hallway. I caught it and threw. Obviously, it didn’t work out. It just made it look bad, because it was the pitcher.”

The Dodgers’ base running, and the Nationals’ ineffective reaction to it, had turned a small rally into a major jam. Fister induced a weak one-hopper by Hanley Ramirez to Desmond, who fired to first for the second out. One more, and the game would remain scoreless.

Facing Adrian Gonzalez, Fister got the result he wanted, a slow groundball. But it trundled past Rendon’s dive and deep into the shortstop hole. Desmond, who had been playing Gonzalez up the middle, snared the ball with a backhand, but he did not control it fully, allowing Gonzalez to cruise into first and Kershaw to score.

Believing the ball had trickled into left field, Gordon bolted home. Desmond still held the ball on the lip of the grass behind third base. A simple throw home would have ended the inning. Oddly, Desmond dashed home holding the ball up, like a scrambling quarterback, before floating a throw home. It sailed over Wilson Ramos’s head and to the backstop. Another run scored, and for good measure, Gonzalez hustled into second.

“Going back, I thought he would realize that I didn’t throw it to first, and he would stop,” Desmond said. “But he just kept on going. I should have just set my feet and made a good throw to home. They would have run him back.”

As if to prove some alien force had not sapped his defensive ability, Desmond ended the inning with a dazzling diving stop up the middle and a rifle throw to first. But the sloppy play prior had put the Nationals in a 2-0 hole.

Gonzalez’s dribbler was typical of the weak hits Fister yielded prior to the fifth inning. Rather than cursing his luck, though, Fister took responsibility for not pitching to his defense.

“I got to make a better pitch,” Fister said. “If the ball is down or if the ball is more in, they don’t bleed. Our defense can get to them. I gave them an opportunity to hit it where we want.”

Fister’s first five innings laid the foundation for an excellent start. But in the sixth, Fister’s sinkers and curves were elevated, and the Dodgers blasted them.

Carl Crawford ripped a single to right to lead off. Fister hung a first-pitch sinker to Juan Uribe, who had hit six home runs all season. Uribe smashed it into the left field bleachers. The Dodgers promptly finished off Fister. Joc Pederson drew a walk, the only one Fister allowed, and A.J. Ellis smoked a single to right field on another fastball left high in the zone.

The Nationals trailed, 4-0, against a pitcher who hasn’t allowed four runs since mid-May. Harper would provide one run. But the Nationals could not overcome their prior mistakes, not against Kershaw.

“He’s a good pitcher,” Williams said. “But on any given day, anybody can beat anybody. Tonight, he didn’t give us many opportunities. That’s why he’s doing so well — because he’s not making many mistakes. Like I said, you’ve got to play a really good game to beat him. And tonight, that wasn’t the case.”