St. Louis took a 3-1 lead in the National League Championship Series and needs only one more victory to earn a shot at its second World Series title in as many years. The Cardinals will host Game 5 on Friday.
Wainwright won his first post-season game this year in three starts after posting a 14-13 record during the regular season. He was backed up by a 12-hit St. Louis attack in which Jon Jay, Matt Holliday and Yadier Molina drove in two runs each.
St. Louis scored twice in the first inning against a shaky Tim Lincecum, a two-time Cy Young Award winner who made his first playoff start of 2012 after having been relegated to the San Francisco bull pen.
Jay singled to open the St. Louis first, Matt Carpenter drew a walk and Holliday singled Jay home. A sacrifice fly by Allen Craig in home the second run of the inning and the Cardinals never trailed.
Holliday, filling in for injured outfielder Carlos Beltran, singled in another run in the fifth and scored later in the inning on a base hit by Molina. A double by Jay delivered two more runs in the sixth, after which Molina had an RBI double in the seventh and then scored on a single from Pete Kozma.
That made things easy for Wainwright, who retired the first five men he faced before giving up San Francisco's a home run by Hunter Pence. That was the only San Francisco run until the ninth, during which Pablo Sandoval hit a two-run blast.
The World Series is scheduled to begin next Wednesday in the home park of the National League representative. Detroit clinched the American League berth earlier in the evening by completing a four-game sweep of the New York Yankees.
A St. Louis-Detroit World Series would be a rematch of the one played six years ago, when the Cardinals downed the Tigers in six games.
St. Louis won last year's World Series in seven games over Texas after twice being one strike away from elimination in Game 6.
The Cardinals were also down to their final strike on two occasions in the ninth inning of the deciding game in the NL Division Series last week before rallying for four runs and stunning Washington 9-7.