Dan Haren carved up Arizona's lineup and the Washington Nationals blanked the Diamondbacks, 2-0, in the middle test of a three-game set from Chase Field.
Haren (10-14) threw 77 of his 107 pitches for strikes as he went seven innings, allowing just four hits and a walk. Drew Storen pitched a perfect eighth to preserve the lead and Rafael Soriano earned his 43rd save of the year.
Chad Tracy had a pair of hits, including his fourth home run of the season, in the triumph. Ryan Zimmerman drove in his 18th RBI in September, matching Jayson Werth's team-leading total for the season's final month.
Brandon McCarthy (5-11) pitched well in defeat, serving up five hits and two runs in seven innings.
Both pitchers kept the offenses at bay until the sixth inning, when Washington manufactured a run to take a 1-0 lead. Denard Span led off the frame with a triple to right and Zimmerman followed with an RBI groundout to short.
Tracy's homer in the top of the seventh spotted the Nats a 2-0 advantage.
Soriano ran into some trouble in the ninth when Martin Prado singled and Miguel Montero walked. Tony Campana pinch-ran for Montero and both runners advanced on a wild pitch, but Matt Davidson struck out swinging and Chris Owings flied to left to end the game.