Nationals 7, Diamondbacks 1: Ryan Zimmerman homered and Stephen Strasburg allowed one hit over six innings as visiting Washington won its seventh straight game.

Strasburg (13-5) exited after fanning six and walking four while throwing 104 pitches.

Sean Burnett, Ryan Mattheus and Craig Stammen followed with three scoreless innings for the Nationals, who moved a season-high 27 games over .500 and remained 4 1/2 games ahead of Atlanta in the National League East.

Washington took an early lead when Bryce Harper’s sacrifice scored Steve Lombardozzi in the third, and Chris Johnson tied the game with an RBI single in the fourth.

Zimmerman broke the tie in the fifth with his two-out, two-run blast to left field off Trevor Cahill (9-10), who gave up four runs over six innings.

Mike Morse extended the lead in the sixth inning when he crushed a solo home run to right center field, giving him three home runs in the last two games.

Lombardozzi went 4-for-5 and Jayson Werth added three hits for Washington, which added a single run in the seventh and two in the ninth on Harper’s sacrifice fly and Adam LaRoche’s RBI double.

Arizona, which has lost six of its last seven, failed to get a runner on base after Johnson’s single with two outs in the bottom of the fourth.

GAME NOTEBOOK: Home plate umpire Dale Scott left the game in the bottom of the fourth after being hit in the chin with a foul ball. …Morse’s home run was measured at 446 feet. …The Nationals improved to a major league-best 9-2 in August. … Arizona placed RHP Josh Collmenter (ulcers) on the disabled list and recalled RHP Brad Bergesen from Triple-A Reno …Harper went 0-for-2 and is hitting just .173 (18-for-104) since the All-Star break.