WASHINGTON -- Clint Robinson, getting a rare start at first base, slapped hands with regular third baseman Anthony Rendon near the pitcher's mound Saturday afternoon after Blake Treinen retired the side in the ninth.

Robinson was in the lineup in place of regular first baseman Ryan Zimmerman while Rendon was back at third after he got a night off Friday.

Starter Tanner Roark threw seven scoreless innings and utility men Robinson and Michael Taylor each had three hits as the first-place Washington Nationals defeated the slumping Philadelphia Phillies 8-0 Saturday.

These days it doesn't really matter who first-year manager Dusty Baker puts in the lineup because all of them are coming through at the plate and in the field.

"We had some good offensive output from some guys," Baker said. "We had a big day out of Clint."

Roark (5-4) gave up six hits and one walk with seven strikeouts before Sammy Solis took over in the eighth. Roark responded after allowing five runs in Cincinnati on June 5.

"It was not just for me, it was for the team," Roark said of bounce-back outing. "You get four runs early it takes a lot of weight off your shoulders."

The Nationals (38-24) are a season-high 14 games over .500 and have won five of their last six. The Phillies (29-33) have lost 16 of their last 21 games after they were a season-best seven games over .500 at 24-17 on May 18.

"He was strong," Baker said of Roark. "I think he only went three innings last time. His pitch count wasn't high. He was sharp this time. He kept the ball down. His slider was good."

The Nationals scored four runs in the second to take a 4-0 lead. Stephen Drew had an RBI single, Roark drove in a run on a fielder's choice via a sacrifice bunt and Taylor and Bryce Harper had RBI singles.

"Play of the game," Baker said of the bunt. "It opened the gates."

The inning unraveled for the slumping Phillies when first baseman Tommy Joseph, fairly new to the position, threw late to the plate on the bunt by Roark that allowed Rendon to score.

"We switch it up now and then," Roark said of his two-strike bunt. "Dusty calls it from the dugout. I missed on the curveball (but) got it down."

Rendon then had a two-run double to give the Nationals a 6-0 lead in the fifth. Drew made it 7-0 with a sacrifice fly off Andrew Bailey. Ben Revere had an RBI single in the eighth to score Chris Heisey, who had a pinch-hit double against Hector Neris, to up the margin to 8-0.

Roark avoided a possible rally in the second when Cody Asche led off with a single and went to third on a double to right by Cameron Rupp. But Roark fanned the next three batters -- all swinging -- to escape the mess in what turned out to be a key fame.

"That second inning kind of set the tone for us," Phillies manager Pete Mackanin said. "Second and third nobody out, and he struck out the side. That kind of set the tone. We just didn't hit."

The losing pitcher was starter Aaron Nola (5-5), who gave up four runs in 3 2/3 innings before lefty Elvis Araujo came on to retire Harper for the final out in the fourth. But Araujo allowed two runs before Bailey arrived from the bullpen in the fifth.

"His breaking ball didn't have a lot of bite," Mackanin said of Nola. "I didn't think it had a tight spin, like he usually does. It was a little flatter. But other than that, I took him out because of the pitch count."

In his previous start at Washington April 28, Nola went seven scoreless innings and allowed just two hits. Nola allowed just five hits and two runs against the Nationals at home May 31 in six innings.

"I felt pretty wild with all my pitches," Nola said. "My curveball was hanging a lot. They put some good swings on those, especially when I had two strikes. It was too much in the zone. And my fastball, my two-seamer was running too much. I couldn't really control it much. And just getting behind guys really hurt me today. It made my pitch count jump up pretty quick, pretty high."

Maikel Franco had two hits for the Phillies and Revere had two hits for Washington, which had 13 hits and has scored at least eight runs in five of its last six games.

NOTES: Washington OF Jayson Werth (2007-10), OF Ben Revere (2013-15) and RHP Jonathan Papelbon (2012-15) all played for the Phillies. ... Nationals hitting coach Rick Schu played mostly third base during his tenure with the Phillies from 1984-87 and 1991 as he hit 24 homers. ... Washington RHP Joe Ross (5-4, 2.92 ERA) will face Phillies LHP Adam Morgan (1-5, 6.70 ERA) in the series finale Sunday. ... Philadelphia 1B Tommy Joseph, who hit two homers Friday, was back in the starting lineup Saturday as manager Pete Mackanin has decided to bench 1B Ryan Howard (.150) and go with Joseph. ... Washington 3B Anthony Rendon was back in the starting lineup Saturday after he got a day off Friday. INF Stephen Drew, who homered Friday while playing third, started at shortstop on Saturday as SS Danny Espinosa got a day off.