Dukes finished with three hits and Guzman had four hits and three RBI. His homers -- a three-run blast in the first inning and a solo shot in the seventh -- were two of the three hit by the Nationals.

Christian Guzman added a first-inning solo homer. Three others had two hits in the Nationals' second three-game sweep this month.

Winning pitcher John Lannan (8-12) gave up two earned runs and four hits, one a two-run first inning homer by Manny Ramirez, in six innings.

Four others had one hit in the Dodgers' seventh loss in a row.

Losing pitcher Clayton Kershaw (2-5) lasted only 2 1/3 innings, giving up five earned runs and five hits.

The Dodgers' deficit behind NL West-leading Arizona grew to 3 ½ games.