WASHINGTON -- The four relievers who pitched Tuesday night for the Arizona Diamondbacks had eventful outings.

T.J. McFarland got the last out in the fifth after starter Taijuan Walker was one out away from qualifying for the win.

J.J. Hoover and Jorge De La Rosa got the last out in the seventh and eighth, respectively, with two runners on base and closer Fernando Rodney picked up his seventh save and lowered his ERA to 11.45 as the Diamondbacks cooled off the first-place Washington Nationals 6-3.

"There were a couple of touch and go moments there," Arizona manager Torey Lovullo said of his bullpen. "I think the highlight for me was Fernando closing it out. He has had some rough outings. He is very professional; he has been working hard."

Washington entered the game with a .295 batting average and a .510 slugging mark, both by far the best in the league.

"I think a lot of credit goes to our pitching staff today," Lovullo said. "It was not a perfect outing for Taijuan. You hold this team to three runs you are doing things right on the mound."

Chris Herrmann went 2-for-3 with a two-run homer as the Diamondbacks went deep three times. Two of the homers came off starter Tanner Roark.

"Tanner is known to throw strikes," Washington manager Dusty Baker said. "They fouled off a whole bunch of pitches. That doesn't fair too well for going deep in a game (for Roark). They were seeing the ball pretty good today. We left a lot of men on base."

The Nationals were 2-for-12 with runners in scoring position and left 10 on base.

Herrmann entered the game batting .167 after going 3-for-16 on a recent homestand. He hit his second homer of the season in a three-run fourth inning that included a solo shot from Jake Lamb.

Chris Owings added an insurance run in the seventh with an RBI single to make it 5-3. Diamondbacks reserve Jeremy Hazelbaker hit his first homer in the ninth for a 6-3 cushion.

The winning pitcher was McFarland (1-0), who allowed no runs or hits in 1 1/3 innings. The Arizona bullpen allowed two hits and no runs in 4 1/3 innings.

Roark (3-1), meanwhile, struggled with his command but got through six innings while throwing 125 pitches. He allowed six hits, two walks and four runs.

"You can't do anything about it," Roark said of the many foul balls Arizona hit early on. "They are trying not to get out. You have to keep battling with good pitches. You can't get frustrated. You have to go out and keep attacking."

Roark battleed through a 19-minute top of the first in which he threw 33 pitches as the Diamondbacks jumped in front 1-0. Paul Goldschmidt's RBI single scored A.J. Pollock, who had led off with a single, stole second and advanced to third on an error by Roark.

Bryce Harper answered for the Nationals in the bottom of the first with an RBI single.

Daniel Murphy gave Washington a 3-1 lead with a two-run single in the third.

Arizona, though, responded with three in the fourth as Lamb hit a solo homer and Herrmann hit a two-run shot to make it 4-3.

McFarland came on with two outs in the fifth for Walker, who gave up three runs and walked five while throwing 117 pitches.

Ryan Zimmerman was 2-for-5 for the Nationals, while Brandon Drury was 2-for-4 for Arizona. The Nationals were held at bay after scoring 23 runs on 23 hits in their last game Sunday against the New York Mets. Washington had scored 73 runs in its previous six games.

"We believe in the process," Lovullo said of the use of his bullpen.

NOTES: Washington RHP Joe Ross was sent to Triple-A Syracuse on Tuesday and RHP A.J. Cole was called up from Syracuse. Ross is 1-0 with a 7.47 ERA this season. ... Washington manager Dusty Baker, one of two African-American skippers in the majors, was asked about the racial slurs Baltimore CF Adam Jones was called Monday in Boston. "It doesn't really surprise me too much because I've been called that word in almost every city that I've played in. So, it don't really shock me too much," Baker said. Added Arizona manager Torey Lovullo: "There is no place or time (for such behavior)." ... Washington LHP Gio Gonzalez (3-0, 1.62) will face Arizona LHP Robbie Ray (2-1, 3.56) on Wednesday.