PHOENIX -- Stephen Strasburg relinquished control and found his command Friday night.

The right-hander 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.

Strasburg (13-5) had been dealing with slight soreness in his mid-back from sleeping awkwardly a couple of starts ago. The stiffness was exacerbated Friday when the game was delayed for nine minutes when Miguel Montero fouled a pitch off home plate umpire Dale Scott's mask, forcing the crew chief from the game.

"I got a little stiff standing out there," Strasburg said. "It happens. I just wanted to go out there and grind through it."

Strasburg pitched into trouble for the first time all game, walking Montero after already having walked Justin Upton. Chris Johnson followed with a sharp single to left for Arizona's lone run.

Nationals manager Davey Johnson took the blame for not pulling Strasburg into the dugout during the delay.

"It really affected him," Johnson said. "We should have known it was going to take 10 minutes and I left him standing out there. My coaches did, too, so I blame them, too."

But Strasburg regained his command by focusing less on his control, struck out the side looking in the fifth and retiring the final seven hitters he faced.

"I just wanted to out there and let it rip and that's when I got my command back," he said.

Strasburg struck out six, issued four walks and threw 58 of his 104 pitches for strikes en route to his second career one-hit outing.

"When he mixes in his changeup, there's no chance," Johnson said.

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.

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.

"It's starting to get more exciting," Lombardozzi said.

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

"They made me work and it was one of those nights I couldn't put anyone away," Cahill said.

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.

Johnson tied the game in the fourth but Washington 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.

"We just didn't have a lot of energy to overcome that tonight," Arizona manager Kirk Gibson said.

Morse led off the sixth with his homer, a 446-foot shot onto the concourse above the wall in center field. 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 runs scored on a double by Jayson Werth.

Notes

• Johnson said Harper will get Saturday off and return for the series finale Sunday.
• Johnson has 17 RBI in 11 games with Arizona.
• Strasburg's four walks were his most since a four-walk, three-inning start June 30 at Atlanta.
• Montero's fourth-inning at-bat was an adventure. One pitch before fouling the ball off Scott's mask, he lost his grip on his bat and it flew into the stands, striking a fan in her abdomen. She was OK and later returned the bat.
• Scott immediately spun and dropped to a knee after he was hit before slowly leaving the field under his own power. C.B. Bucknor came in from third base to replace Scott.
• Johnson is 3 for 5 with three RBI 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 afternoon 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.