PHILADELPHIA -- Washington Nationals right-hander Tanner Roark, uncommonly poor in his previous outing, was as good as ever against the Philadelphia Phillies on Monday night.

Roark combined with two relievers on a four-hit shutout as the Nationals blanked the Phillies 4-0.

Roark (14-7), who surrendered five runs (four earned) over five innings in a 10-8 loss to Baltimore on Aug. 24, went seven unblemished innings, allowing four hits while striking out five, walking one and hitting a batter.

"I kind of knew after the last one, he'd respond," Washington manager Dusty Baker said. "He was sharp, threw some key double plays."

Roark improved to 3-0 with a 0.64 ERA in four starts against the Phillies this season. He has also thrown seven or more shutout innings eight times, most among major league pitchers, and has been the starting pitcher in six of the Nationals 10 shutouts to date.

"The third inning I started executing and using my upper body," Roark said.

He also benefitted from a stiff wind that blew in from center field. It notably knocked down a second-inning shot in that direction by Philadelphia's Cameron Rupp, which Washington centerfielder Trea Turner caught at the fence.

The Phillies, however, only put two runners on against Roark once, in the third, and he quickly retired Odubel Herrera and Maikel Franco to quell the threat. Washington also turned double plays in the fourth and sixth.

"He's a good pitcher," Phillies manager Pete Mackanin said of Roark. "He mixes it up. He locates. He does all the things we try to tell our pitchers to do. He's poised. Good mixture of pitches and he moves the ball around, keeps you rocking back and forth. He upsets your timing."

Marc Rzepczynski retired all three hitters he faced in the eighth and Mark Melancon, working in a non-save situation, did the same in the ninth.

Jayson Werth homered for Washington, which ran its winning streak against Philadelphia to seven. The Nationals, however, won for just the third time in nine games overall.

The Phillies lost for the third time in four games and were shut out for the seventh time this season.

Phillies starter Jake Thompson (1-4) went seven innings, the longest of five outings the rookie has made in the major leagues this season. Thompson, who tweaked his delivery after pitching to a 9.78 ERA in his first four starts, allowed two runs and seven hits while striking out three and walking one.

"It was night and day from my performance my first four that I've had," he said. "It's kind of a relief. It feels a lot better."

Werth hit a solo homer with one out in the first inning, launching Thompson's 2-1 slider into the seats in left field. It was the 19th homer of the season for the former Phillie, his third in four games and his seventh in August.

Bryce Harper walked one out later and scored from first on a single by Anthony Rendon, making it 2-0.

Both pitchers settled in after that. The Phillies managed to put only one runner in scoring position in Roark's last four innings and Thompson fanned Turner with two on to end the seventh.

"That was huge," Mackanin said. "Great to see. I'm real pleased with that, and that's just what he needed. He needed a real positive outing."

Clint Robinson and Turner added RBI singles off reliever Frank Herrmann in the ninth, giving Washington a 4-0 cushion.

NOTES: Washington LF Jayson Werth has reached base in 54 of his last 55 games. He also has 63 career homers in Citizens Bank Park, fifth-most in the history of the stadium. ? The Nationals recalled OF Michael A. Taylor from Triple-A Syracuse and optioned RHP Lucas Giolito to the same club prior to Monday's game. ... Phillies C A.J. Ellis, who was acquired in a trade with the Los Angeles Dodgers last Thursday, delivered a tie-breaking two-run double in the seventh inning of his debut with the club Sunday, a 5-1 victory over the New York Mets. According to the Elias Sports Bureau, he is only the second major league player this season to deliver a game-winning RBI in the seventh inning or later in his first game for a team. The other was Washington 2B Daniel Murphy, who accomplished the feat on Opening Day in a 10-inning victory at Atlanta. ... Washington RHP Stephen Strasburg, on the disabled list since Aug. 21 with a sore right elbow, threw a bullpen session before the game, according to MLB.com. ... The announced crowd of 16,056 was the smallest of the season in Citizens Bank Park.