St. Louis Cardinals Carlos Beltran celebrates his three run home run in the third inning against the Pittsburgh Pirates with teammates in the dugout during Game 1 of the National League Division Series at Busch Stadium in St. Louis on October 3, 2013. UPI/Bill Greenblatt

Carlos Beltran celebrates his three run home run in the third inning against the Pittsburgh Pirates. UPI/Bill Greenblatt

Carlos Beltran’s three-run homer sparked a seven-run third inning as the Cardinals’ bats backed Adam Wainwright with a 9-1 win over the Pittsburgh Pirates in their NL division series opener.

Wainwright remains unbeaten in the postseason, going to 3-0 with a 2.27 ERA in 14 games. Wainwright allowed a run on three hits in seven innings, striking out nine without a walk. His only run allowed was a homer by Pedro Alvarez to start the fifth.

Wainwright started the third by drawing a lead off walk and Matt Carpenter singled to right. Beltran’s homer put the Cards on top 3-0, and Jon Jay later walked with the bases loaded. David Freese hit a single that cleared the bases when right fielder Marlon Byrd’s throw to the plate got away.