The Reds and Pirates each have a magic number of two to close out Washington and clinch a playoff spot. Cincinnati and Pittsburgh trail NL Central leader St. Louis by 2 1-2 games, pending the Cardinals' night game at Milwaukee.
Jay Bruce hit a three-run double and Todd Frazier followed with a homer that capped a five-run burst in the first inning. Bronson Arroyo(14-11) made it stand up, lasting five innings to win for the first time in nearly a month.
Neil Walker hit his 13th homer of the season, but Pittsburgh stumbled in its home finale.