Lackey has already made two appearances in the series. He took the loss in Game 2 after being charged with three runs in 6⅓ innings. Lackey exited that game with a 2-1 lead.
The 35-year-old right-hander made his first relief appearance since 2004, and only the fourth of his career, in Game 4. Lackey tossed a scoreless eighth inning in Boston's 4-2 win.
Michael Wacha will take the mound for the Cardinals in their second elimination game of the postseason. Wacha also started the first such contest and tossed 7⅓ innings of one-hit ball in a momentum-changing win over the Pittsburgh Pirates in Game 4 of the NLDS.
The 22-year-old rookie followed that performance with 19 consecutive scoreless innings, a streak that was broken by David Ortiz's two-run homer in the sixth inning of Game 2. Wacha still earned the victory after allowing a pair of runs on three hits in six innings.
Joe Buck and Tim McCarver will be in the broadcast booth for first pitch, which is slated for 8:07 p.m. ET.