Stephen Strasburg allowed one hit over six innings and Ryan Zimmerman homered to help the Washington Nationals rout the slumping Arizona Diamondbacks 9-1 on Friday night for their seventh straight win.

Michael Morse homered, Steve Lombardozzi had a career-high four hits and scored three runs and Bryce Harper added two sacrifice flies for the Nationals, who remained 4 1-2 games ahead of Atlanta in the NL East.

Strasburg (13-5) issued four walks, including consecutive passes to Justin Upton and Miguel Montero in the fourth that led to the Diamondbacks' lone run.

The right-hander struck out six and threw 58 of his 104 pitches for strikes en route to his second career one-hit outing.

Strasburg raised his season innings total to 133 1-3, just under 27 fewer than the 160-inning cap the Nationals have planned for him in his first full season back from Tommy John surgery.

Arizona starter Trevor Cahill (9-10) went six innings, allowing four runs, six hits and three walks while striking out four.

The Diamondbacks have lost five of seven.

Lombardozzi tripled and scored on Harper's first sacrifice fly to give the Nationals a 1-0 lead in the third.

Arizona tied the game in the fourth when Chris Johnson followed the consecutive walks to Upton and Montero with a line single to left to make it 1-1.

But Washington answered quickly and took the lead for good in the fifth when Lombardozzi singled with one out and Zimmerman homered a dozen rows into the stands in left to put the Nationals ahead 3-1.

Morse led off the sixth with his homer, a 446-foot shot onto the concourse above the center field wall. Lombardozzi singled again in the seventh and scored on a throwing error for his third run of the game.

Washington added four runs in the ninth off Mike Zagurski, the Diamondbacks' fourth pitcher, the last two coming on a double by Jayson Werth down the left-field line.

NOTES: Strasburg's four walks were his most since a four-walk, three-inning start June 30 at Atlanta. . Montero had an eventful at-bat before drawing his walk in the fourth. First, he lost his grip on his bat and it flew into the stands, striking a fan in her abdomen. She was OK, but home plate umpire Dale Scott was less fortunate. On Strasburg's next pitch, Montero fouled a pitch directly off the bottom half of Scott's mask. Scott immediately spun and dropped to a knee before slowly leaving the field under his own power. C.B. Bucknor came in from third base to replace Scott after a nine-minute delay. . Johnson is 3 for 5 with three RBIs in his career against Strasburg. . Morse's home run extended his suddenly shortened hitting streak to eight games. Morse had an 18-game streak before a scoring change made Friday aftermoon turned his lone hit Aug. 2 to an error. . Before the game, the Diamondbacks placed RHP Josh Collmenter on the 15-day DL because of ulcers and recalled RHP Brad Bergesen from Triple-A Reno. Collmenter is 3-3 with a 4.24 ERA in 22 games, including nine starts.