Reds starter Tim Adleman (3-4) retired the first 10 Cardinals he faced and went a career-long seven innings. It was his first win since Aug. 19.
Steve Selsky went 5-for-5 including a homer, four RBI and scored three runs. He's the first Reds rookie to have five hits in a game since Wade Rowdon against the Mets on July 9, 1986.
The Reds improved to 6-4 in their last 10 games against the Cardinals, who fell one game behind the idle San Francisco Giants for the second wild card spot with six games to go.
Votto and Duvall hit back-to-back homers in the first to start the offensive barrage. They combined for seven hits, six runs, three homers and six RBI.
Duvall's three-run homer in the fifth gave him a career-high five RBI. It was the third multi-homer game and his first four-hit game of his career.
The Reds sent 12 men to the plate in a seven-run fourth and 11 more in a four-run fifth.
Brandon Phillips had his 14th career four-hit game.
Jaime Garcia (10-13) lasted just one inning in his shortest outing of his career and possibly last as a Cardinal. Jose Peraza and Phillips singled against him and combined to steal three bases and almost a fourth, but Peraza was thrown out at third.
Garcia drew boos from the 34,942 fans after Phillips easily swiped third base after it appeared Garcia didn't bother to look him back. It was the first time in 240 regular season games that the Cardinals failed to drew at least 40,000, dating back to Sept. 24, 2013.
Cardinals: IF Matt Carpenter (right ring finger) was out of the lineup and it is uncertain if he will play tomorrow. ... SS Aledmys Diaz left the club to join Jose Fernandez' family in a private ceremony. Diaz and Fernandez, the Miami Marlins pitcher who died in a boating accident early Sunday morning, were boyhood friends.
Reds: RHP Robert Stephenson (2-2, 5.59 ERA) gave up four runs in 3 2/3 innings to the Cubs last Wednesday. It is his first career appearance against St. Louis.
Cardinals: RHP Adam Wainwright (12-9, 4.57 ERA) has given up four runs while failing to get out of the fifth inning in each of his last two starts. He is 0-1 with a 6.06 ERA in three starts this season against Cincinnati.