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Stephen Strasburg tries to pitch the Washington Nationals to their seventh straight win on Friday when they begin a three-game series with the Arizona Diamondbacks at Chase Field.

Strasburg won for the third time in four decisions on Sunday, as he held the Miami Marlins to three hits over six scoreless innings to run his record to 12-5 on the year, while lowering his ERA to 2.97. He also struck out six and his 160 on the year are second only to New York's R.A. Dickey in the National League.

"I'm just still learning how to pitch and call a game, really pick up on little things that happen in a game that can really be used to your advantage," said Strasburg, who did not get a decision in his only other appearance against the Diamondbacks.

"Sometimes you've just got to get a feel for a game, and you give up a couple runs early. The big thing is to give your guys a chance to put some runs on the board and keep it close."

As good as Strasburg has been for the Nationals this season right-hander Jordan Zimmerman may be better. Zimmerman tossed six scoreless innings on Thursday and Michael Morse hit two home runs to power Washington past the Houston Astros, 5-0.

Zimmermann (9-6) gave up just three hits, tied a career-high with 11 strikeouts and did not walk a batter. He has won six straight decisions.

"Jordan has been, probably, consistently as good as anybody in the league, no question about it," said Nationals manager Davey Johnson. "I'm very comfortable when I watch him because he's in attack mode. He's a bear out there."

Morse also extended his hitting streak to 18 games.

Ryan Zimmerman and Adam LaRoche both added an RBI for the NL East-leading Nationals, who have won eight of their last nine games and 16 of their last 20. They haven't won seven in a row since an eight-game run last June.

Arizona, meanwhile, enters this series after taking two of three from the Pittsburgh Pirates. In Thursday's rubber match, Jason Kubel hit a pair of two-run homers and the Diamondbacks rolled to a 6-3 win.

Wil Nieves also hit a two-run homer for the Diamondbacks, who went 6-4 on a 10-game road trip. It was Arizona's first winning road trip since May 14-20.

Arizona starter Joe Saunders (6-8) gave up three runs -- two earned -- on seven hits over seven innings. He struck out three and did not issue a walk.

"I was making pretty good pitches. They were still finding holes," Saunders said. "I just kept telling myself, 'Hey, keep making good pitches and keep pounding the strike zone and it's going to start going your way.' I'm going to try to stay as positive as I could."

Tonight, the D'backs turn to righty Trevor Cahill, who is 9-9 with a 3.76 ERA. Cahill did not get a decision on Sunday in Philadelphia, as he allowed three runs and six hits in seven innings of a 5-4 loss.

Cahill beat the Nats earlier in the year in his only other start against them.

Washington took two of three from Arizona earlier in the year.