Down 3-1 and held to one hit for eight innings, the Indians found more of the late-inning magic that has carried them this week.
Delino DeShields — who broke up Pittsburgh's no-hit bid with a bunt single in the seventh — hit an RBI single one out later.
Until the ninth, the Indians did little against Pittsburgh starter Mitch Keller and three relievers.
Gregory Polanco hit a two-run homer in the fourth inning off Indians starter Carlos Carrasco, but the Pirates couldn't hold on and dropped to 2-16 against AL Central teams.
UP NEXTAaron Civale (4-5), who will pitch in relief for the Indians during the wild-card round, makes his final regular-season start against Pirates right-hander Joe Musgrove (0-5).