PITTSBURGH — Randal Grichuk scored after an error by Pirates shortstop Jordy Mercer, capping a frantic ninth-rally that lifted the surging St. Louis Cardinals over Pittsburgh 4-3 on Friday night.

The playoff-chasing Cardinals won their fourth straight, despite trailing by a run entering the ninth. Stephen Piscotty led off with a double to right against closer Felipe Rivero (5-3), and Jedd Gyorko followed with a pinch-hit RBI single. After Tommy Pham’s single, Grichuk pinch-ran for Gyorko at third. He scored when Mercer misplayed Dexter Fowler’s sharp groundball.

St. Louis began a three-game set in Pittsburgh just 1½ games behind Colorado for the second wild-card spot in the National League after taking three straight against Cincinnati, a resounding bounce back after getting swept last weekend by the Chicago Cubs.

Former Pirates reliever Juan Nicasio (4-5) got the win after working the eighth and ninth. Fowler and Piscotty had two hits each.

David Freese had an RBI double for the Pirates.