The Washington Nationals have risen to the top of baseball and the National League East by beating contenders and cellar dwellers. They carry the best road record in the sport, and they have an even better record at home. But for some inexplicable reason, the Miami Marlins have been an annoying thorn in their side.

The Nationals still have a cushion in the NL East race. But again, their division nemesis claimed a game from them, a deflating 8-0 loss on Sunday afternoon. The Marlins, far from playoff contention, finish the season series with the Nationals in an even 9-9 split.

The Nationals, at times this season, stumbled against the Marlins’ mediocre starting rotation, and below-league-average bullpen and lineup. Over the course of a 162-game season, that is bound to happen against someone. Despite the loss, the Nationals hold a 51 / 2-game division lead over the Atlanta Braves. They finished a homestand 8-3 and head to New York and Atlanta for six games.

“We caught a good pitcher on his game,” first baseman Adam LaRoche said. “We were a little bit off ours. Overall it wasn’t a sloppy game. It was just a good old butt-whipping.”

Edwin Jackson suffered through one of his worst starts of the season, allowing six runs on nine hits over 42 / 3 innings. Third baseman Ryan Zimmerman and shortstop Ian Desmond received rare days off, their missing presences most obvious on defense. And Marlins right-handed starter Ricky Nolasco completely fooled the Nationals hitters for a second straight complete game, running his scoreless streak against them to 22 innings.

Nolasco used an array of pitches, relying heavily on his curveball, slider and change-up. He allowed only four hits: singles by Michael Morse, Bryce Harper and Steve Lombardozzi, and a double by Chad Tracy. Three of those hits came in the eighth inning or later. In the first five innings, the Nationals hit into two double plays.

In a third-inning, four-pitch strikeout of Danny Espinosa, Nolasco tossed two curveballs and two sliders. Against Tracy in the second inning, the at-bat went like this: change-up, fastball, slider, change-up and a curveball that was hit for a flyout.

Most of the Nationals’ at-bats against Nolasco weren’t fruitful until it was too late. In two starts earlier this season, the Nationals shelled him for a total of eight runs over two losses. But in the past two weeks, it was the reverse.

“He can get nasty when he starts throwing that change-up and that curveball and hitting the corners with his fastball,” Nationals Manager Davey Johnson said. “He cuts it in on left-handers, he does all kinds of stuff with the ball. . . . The guys say when he wants to, he’s one heck of a pitcher.”

Marlins hitters, on the other hand, pounced on Jackson. He allowed three straight singles in the second inning to the sixth, seventh and eighth hitters in the Marlins’ order, all hits just beyond the reach of Nationals infielders. Zimmerman and Desmond, stalwarts on the left side of Washington’s infield, watched from the dugout. Zimmerman’s day off was planned, but Desmond, after playing two full extra-inning games in as many days and nursing a minor hamstring strain for two weeks, asked Johnson to rest.

Tracy started at third base and Lombardozzi at second base, and Espinosa slid over to shortstop. They are all capable defenders, but Zimmerman and Desmond are known for their range, and Johnson was reminded of that watching on Sunday.

“Those guys out there can play, too,” he said. “Those were just some well-placed balls, hard-hit. I thought Jackson was going to throw a nasty game, the way he started, and then he just started getting more deliberate and more deliberate.”

In the second inning with two runners on base, Nolasco smacked a ball to deep center. Harper ranged back but lost the ball in the sun, allowing it to fall in for a two-run double. Espinosa bobbled the relay throw, missing a chance to cut down Rob Brantly at home. And with that, the Marlins had a 3-0 lead.

“It was one of the brightest days I can remember playing in,” right fielder Jayson Werth said. “Sun was in charge out there today.”

Jackson surrendered two more runs in the fourth inning, and he was yanked from the game with two outs in the fifth after 80 pitches. It was his shortest outing since his shelling on June 28 in Colorado, and the second-most runs he has allowed in a game this season. Johnson was concerned Jackson was too slow on the mound, maybe tired or weighing every hit too much. Pitching coach Steve McCatty told him to pick up the pace.

“I’ve just got to do a better job of making pitches out of the stretch with men on base, a better job of damage control,” Jackson said.

Marlins cleanup hitter Giancarlo Stanton continued to torment the Nationals. He crushed the first pitch he saw from reliever Christian Garcia in the seventh. Stanton homered in each game this series, and hit .405 against the Nationals this season.

The Nationals dropped another game against their division adversary and won’t face them again. Instead, they begin two three-game series against the Mets and the Braves, teams they have a combined 21-9 record against. The Philadelphia Phillies, at 7-5, are the lone division opponent with a winning record against the Nationals this season, and the teams will play each other six more times. As for the Marlins, they took advantage of their last chance to face this Washington team.

“Everything they hit today found a hole,” LaRoche said. “What few balls we did hit didn’t find any holes until late. One of those days. . . . Oh well, go to New York, take care of business.”