WASHINGTON — Matt Kemp returned to the lineup with a home run and a double in the second inning, then limped off the field in the ninth.

A too-good-to-be-true day for the Los Angeles Dodgers turned out to be just that. They completed a sweep of the Washington Nationals on Sunday with a 9-2 win that kept them a half-game out of first place in the NL West.

The game marked the first time Kemp, Hanley Ramirez and Carl Crawford were in the starting lineup at the same time. It might be a few days before it happens again — because Kemp hurt his left ankle sliding into home plate on a force play, a needless injury that came from lack of hustle.

"It's not bad. I hope it's not bad," Kemp said. "The biggest thing will be tomorrow when I wake up and see how it feels."

Manager Don Mattingly said the injury appeared to be a sprain, and that no X-rays were planned. Nor did he expect Kemp to return to the disabled list.

"That's what I said last time, too," Mattingly said with a chuckle.

Activated from the 15-day DL before the game — he had left shoulder inflammation following offseason surgery — Kemp led off the second with a homer that bounced among the cherry trees beyond the left-field stands. He then doubled home Andre Ethier in a seven-run inning against Jordan Zimmermann (12-5), quickly turning a much-anticipated matchup of All-Star aces into a rout.

Clayton Kershaw (9-6) allowed two runs and two hits over seven innings with nine strikeouts and no walks, putting his major league-best ERA at 2.01.

The Dodgers were 9½ games out of first on the morning of June 22, but they've since gone on a 20-5 splurge. Sunday's win temporarily pulled them even with the Arizona Diamondbacks, who then moved a half-game ahead when they beat San Francisco 3-1 later in the day.

While the Dodgers are brimming with confidence, the series was a nadir for the Nationals, who have dropped eight of 10 and lost all semblance of the "Natitude" that produced the best record in the majors a year ago.

After losing close games Friday and Saturday because of a collapse in clutch hitting — 2 for 21 with runners in scoring position — the Nationals on Sunday looked like a once-promising TV series that has finally jumped the shark. They hit only six balls out of the infield in Kershaw's seven innings, including two mostly meaningless homers by Jayson Werth after the game was well out of reach.

Manager Davey Johnson experimented again with Bryce Harper batting leadoff; Harper went 0 for 4 with three strikeouts. Adam LaRoche returned after missing two games with the flu and went 0 for 3. Scott Hairston started in place of Denard Span and went 0 for 3. Zimmermann, who has been battling a sore neck, lasted just two innings, the shortest outing of his career.

"There's a good attitude," Johnson said. "I'm the one that's frustrated. I'm the one that has trouble sleeping."

Everyone in the Dodgers' starting lineup except Kershaw scored at least one run, and even he had an RBI groundout. Kemp added another hit, an RBI single in the fourth. Ramirez lifted his average to .393 with a three-run homer and a single, and Crawford had three hits and a walk.

Kemp also reached base with a walk in the ninth and was on third when Crawford hit a slow roller toward first with two outs. It would have been an infield hit had Kemp hustled home. Instead, he took his time and allowed the Nationals to make a play at the plate. He was hurt sliding into the catcher.

"I wasn't running hard," Kemp said. "I took a hit away from CC. CC has every reason to be mad at me because that was my fault, and the results of me not running hard to home plate kind of tweaked my ankle a little bit."

NOTES: Dodgers rookie Yasiel Puig didn't start after going 0 for 9 with five strikeouts Friday and Saturday. "He seemed a little lost to me the last couple of days, just kind of confused at the plate," Mattingly said. ... It was the first road sweep for Los Angeles against the Nationals franchise since taking three from the Montreal Expos from May 24-26, 1996. ... The Dodgers optioned OF-1B Scott Van Slyke to the minors to make room for Kemp.