PHOENIX -- The newest additions to the Washington bullpen came through when called upon to help deliver a victory to their new team.
Sean Doolittle stranded the potential tying run by escaping a jam for his second save for Washington, and Ryan Madson tossed a scoreless eighth inning as the Nationals held off the Arizona Diamondbacks 4-3 on Saturday night.
"The game can really speed up on you once you start getting guys on base," said Doolittle, who with Madson arrived in a trade with Oakland earlier in the week. "The crowd and the energy of the stadium can kind of take over and ... you have to be mindful enough to step off the mound, slow the game down a bit, kind of press reset."
Bryce Harper homered and drove in two runs, and starting pitcher Tanner Roark struck out a season-high 11. Roark (8-6) gave up two runs and three hits in seven innings for the NL East-leading Nationals.
"Curveball felt good. Just keep the hitter guessing," Roark said.
Harper hit his 25th home run on a full-count offspeed pitch from Anthony Banda (0-1), who lost in his major league debut.
Chris Iannetta hit a two-out RBI double in the bottom half, but the Nationals opened a 4-1 lead with a three-run sixth.
Harper hit a run-scoring double and scored on Ryan Zimmerman's double, and Anthony Rendon beat out an RBI single that sent Zimmerman home.
"They had a young guy out there that throws the ball really hard, has good command. He's going to be really good in the next couple of years for sure," Harper said of Banda. "Just got him this time and got a few runs up there."
A.J. Pollock tripled in the bottom half and scored on Jake Lamb's groundout, and Arizona reliever Jorge De La Rosa got out of bases-loaded trouble in the seventh when he struck out Harper and Zimmerman.
Doolittle, acquired from Oakland last weekend, walked Lamb leading off the ninth. Iannetta hit a broken-bat grounder to third, and Rendon's throw to second went into right field for an error that put runners on the corners.
Paul Goldschmidt hit a sacrifice fly, Chris Owings flied out and Doolittle struck out Ketel Marte for his second save with the Nationals.
"Madson's been great for us. Doolittle ... he never panics. It was great to see. It's a lot of fun to have a back end like that," Harper said.
Banda allowed four runs and seven hits in 5 2/3 innings, struck out five and walked none. He was optioned back to Triple-A Reno after the game.
"I felt confident. I threw the ball in the zone and kept attacking hitters," Banda said. "I made a couple of mistakes, Harper and the middle of the lineup."