Edging ahead ... Koji Uehara celebrates with Boston teammate David Ross. Photo: Getty Images
Pitcher Jon Lester smothered St Louis on four hits into the eighth and David Ross hit a tiebreaking RBI double in a two-run seventh inning as the Boston Red Sox beat the Cardinals 3-1 to take a 3-2 World Series lead.
David Ortiz's RBI double in the first put the Red Sox ahead until Matt Holliday hit his second home run of the series in the fourth.
Lester beat Adam Wainwright for the second time this series, striking out seven and walking one in 7 2-3 innings, and Koji Uehara finished the four-hitter for his second save.
Boston can win their third title in a decade on Wednesday night, when the series resumes at Fenway Park.