The Diamondbacks (19-7) tied their best start in franchise history while becoming the first NL team to win its first nine series since the 1907 Chicago Cubs, who won their first 11. Seattle won its first nine in 2001.
Ryan Zimmerman and Howie Kendrick homered for the Nationals, who have lost six of seven.
Nick Ahmed opened the 10th inning with a double off left-hander Sammy Solis (0-1) and Peralta walked with one out. With right-handed hitter Chris Owings in the on-deck circle ostensibly to bat for lefty Jarrod Dyson, Nationals manager Dave Martinez brought in right-hander Austin Adams.
Since Owings had not been announced, however, Dyson remained in the game and walked to load the bases. Pollock walked on a 3-2 pitch to force in the go-ahead run.
Yoshihisa Hirano (2-0) pitched the ninth inning and Brad Boxberger pitched the 10th inning for his eighth save in as many chances and his second in the series.
Zimmerman doubled with two outs in the 10th, and the Diamondbacks intentionally walked Bryce Harper before Kendrick walked and Michael A. Taylor grounded out to end the game.
Arizona starter Patrick Corbin gave up seven hits and three runs in 6 2/3 innings, with seven strikeouts and one walk. He was attempting to become the second five-game winner in majors, joining the Nationals' Max Scherzer.
Washington starter Jeremy Hellickson gave up five hits and two runs, both Peralta's homers, in 5 1/3 innings. He struck out one and walked one in his third start of the season after signing a minor league deal late in spring training.
Zimmerman's two-run homer broke a scoreless tie in the third inning before Peralta tied it with homers in the fourth and sixth. Zimmerman, who hit second in the order for the first time since June, 6, 2015, has three homers in his last nine games.
Kendrick homered in the last of the sixth to make it 3-2 lead and extend his hitting streak to six games.
Pollock tied the game at 3 in the eighth inning with a two-out single off Ryan Madson after singles by Ahmed and Peralta.
--Field Level Media
Arizona | Washington | |
Patrick Corbin | Player | Jeremy Hellickson |
No Decision | W/L | No Decision |
6.2 | IP | 5.1 |
7 | Strikeouts | 1 |
7 | Hits | 5 |
4.05 | ERA | 3.38 |
Arizona | Washington | |
David Peralta | Player | Ryan Zimmerman |
3 | Hits | 2 |
2 | RBI | 2 |
2 | HR | 1 |
9 | TB | 6 |
.750 | Avg | .400 |
Team | Hits | HR | TB | Avg | LOB | K | RBI | BB | SB | Errors |
Arizona | 9 | 2 | 16 | .243 | 16 | 7 | 4 | 4 | 0 | 0 |
Washington | 8 | 2 | 17 | .222 | 13 | 10 | 3 | 3 | 1 | 0 |