Michael Wacha of the Cardinals gets the call but has only appeared in 15 games.
Wacha has appeared in two games against the Pirates and dominated. He showed up in relief on Aug. 14, retiring all six batters he faced with four strikeouts. On Sept. 8 he started against the Pirates, working seven shutout innings and allowing only two hits.
Source: Matt Snyder, CBS Sports Can Rookie Wacha Step Up In Do-Or-Die Game? by Charles Mager