The Cardinals turned to their bullpen tied 3-3 with the Reds in the seventh inning.
Righthanded reliever Matt Bowman replaced starter Michael Wacha and induced back-to-back groundouts before he surrendered a pinch-hit double to Jordan Pacheco.
Lefty Kevin Siegrist then came in for the final out, striking out leadoff man Zack Cozart on three pitches.
Wacha surrendered seven hits and three runs (one earned) through six innings. He walked one and struck out five.
Carpenter's homer ties it
Matt Carpenter's solo homer to right center field in the fifth inning locked the Cardinals and Reds in a 3-3 tie.