The West Division-leading Diamondbacks (19-7) rallied from a 3-2 deficit to post a 4-3 10-inning victory Saturday to become only the second team to win their first nine series of the season, trailing only the 1907 Chicago Cubs, who won 11 straight.
David Peralta homered twice for Arizona, and A.J. Pollock drove in the tying run with an eighth-inning single and the go-ahead run with a bases-loaded walk in the 10th inning.
"When you have a good team you never feel like you're out of the game," Pollock said. "You don't know who it's gonna be, but we've had a lot of different guys step up during the year and we feel like if we're close at the end of the game we have a chance."
Starter Patrick Corbin allowed three runs in 6 2/3 innings, but the bullpen was perfect, providing 3 1/3 scoreless innings. Brad Boxberger ensured the series win when he pitched out of a two-out bases-loaded situation in the 10th for his eighth save.
"It's a good start," Boxberger said of the nine series wins. "Go for the sweep tomorrow. Like to mix a couple of those in when we have the opportunity to and just keep rolling."
Washington manager Dave Martinez, whose team has lost six of seven, shook up his lineup. It paid dividends, but not enough.
Struggling Ryan Zimmerman, moved from the cleanup spot to second, slugged a two-run homer to give Washington an early lead and doubled in the 10th. Howie Kendrick, the team's hottest hitter of late, was moved to the cleanup spot behind Bryce Harper and smacked a solo homer to make it 3-2 in the sixth.
"I've done it before with Joe (Maddon), moving guys around. Just kind of shake it up a bit," Martinez said before the game. "Howie's hitting the ball really well. I think Zim's hitting the ball hard. I just want to shake things up a little."
Arizona's Robbie Ray (2-0, 5.13 ERA) opposes Gio Gonzalez (2-2, 3.04) in Sunday's finale.
Gonzalez was lifted after issuing a leadoff walk in the sixth inning of his last start Leading 2-1, Martinez went to his bullpen and Shawn Kelley allowed a two-run homer in what ended up a 4-2 loss to the San Francisco Giants on Monday.
"I'm a starting pitcher, if I could go perfect every game I would, but right now sometimes I got to hit some walls to break through," Gonzalez told the Washington Post. "Apparently, I just got to some way somehow convince I can go past five innings."
Gonzalez went six innings in his first start of the season has not topped 5 1/3 innings in any of his past four outings, throwing 100 pitches once.
He is 2-1 with a 3.23 ERA in seven starts versus Arizona.
Ray was a minor league pitcher in the Nationals system before he was traded to the Detroit Tigers in December 2013, as Washington acquired veteran pitcher Doug Fister. Ray was dealt to Arizona after the 2014 season.
He struck out a season-high 11 batters on Tuesday in Philadelphia, but did not figure in the decision. He gave up three runs, five hits and three walks in 4 2/3 innings of a game the Diamondbacks won 8-4.
Ray's former team has not been kind to him as he is 0-4 with a 6.65 ERA in four starts versus the Nationals.