Buster Posey drove in three runs and the San Francisco Giants took advantage of some clunky defense by St. Louis first baseman Matt Adams, beating the Cardinals 6-4 on Wednesday night to move within one victory of the World Series.

Chasing their third title in five years, the Giants lead the best-of-seven NL Championship Series 3-1 after poor throws cost the Cardinals yet again.

October ace Madison Bumgarner can pitch San Francisco to another pennant Thursday night at home in Game 5. Struggling All-Star Adam Wainwright starts for St. Louis, now facing the same daunting deficit the Giants overcame to beat the Cardinals in the 2012 NLCS.

Kansas City awaits the winner after completing its ALCS sweep of Baltimore earlier in the day. The wild-card Royals will host Game 1 of the World Series next Tuesday night.

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