Werth finished 2-for-2 with an RBI and two walks as Washington took the opener of a three-game series.
Gio Gonzalez (4-3) logged his first victory since May 5 -- a span of eight starts during which he recorded seven no-decisions. The left-hander allowed two runs on nine hits over 6 1/3 innings, walking one and striking out four.
Diamondbacks starter Trevor Cahill (3-9) extended his winless streak to seven appearances, yielding six runs on eight hits over five full frames.
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