The Pirates (93-68) hit six home runs, including two by second baseman Neil Walker, as they beat the Reds (90-71) for the second straight game.
The loss means Cincinnati will now be the second Wild Card in the NL, and will play a road game in Pittsburgh to advance to the second round of the playoffs.
Pedro Alvarez hit his 36th home run of the season in the win tying with Arizona’s Paul Goldschmidt for the NL lead.
The Pirates chased Reds starter Bronson Arroyo (14-12) in the fifth inning. Arroyo finished the game pitching 4 2/3 innings, allowing six runs, eight hits and five home runs.
The Pirates and Reds will finish their seasons Sunday against each other and then play their one-game playoff on Tuesday.
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