Brady Singer (4-0, 3.62 ERA) will start the first game for Cincinnati. Reds manager Terry Francona has not announced his starter for the nightcap.
Miles Mikolas (0-2, 5.70 ERA) will start for the Cardinals in the opener, and Steven Matz (2-0, 1.80 ERA) will go in the second game.
Cincinnati, which has won five straight games, was to be without one of its big bats on Tuesday after Austin Hays tweaked his hamstring running the bases in the sixth inning of Monday’s 3-1 win over the Cardinals. The results of an MRI on Hays were pending.