The wild-card Pittsburgh Pirates beat top seed St. Louis 5-3 on Sunday to move within one victory of reaching the National League Championship Series (NLCS).

The Pirates, playing in the postseason for the first time in 21 years, rewarded their success-starved fans at rocking PNC Park by taking a 2-1 lead in the best-of-five National League Division Series.

"Unbelievable," Canadian-born catcher Russell Martin said of the constant roar from the crowd of more than 40,000 at the sold-out stadium.

"Pittsburgh's really coming strong. We love it. We want to keep it going."

The Pirates can clinch a berth in the best-of-seven NLCS, which produces the National League representative for the World Series, when they host Game 4 on Monday.

St. Louis tied the contest 3-3 on a home run by slugger Carlos Beltran in the eighth inning.

But Pittsburgh came right back with a pair of runs in the bottom half of the inning on RBI singles by Martin and Pedro Alvarez.

Alvarez delivered his go-ahead hit off rookie left-handed reliever Kevin Siegrist, who pitched to a remarkable 0.45 earned run average in just under 40 innings during the regular season.

"He's a pretty good pitcher," the left-handed hitting Alvarez said about Siegrist.

"He's got good stuff. I had to be ready to hit and put good contact on the ball."

Martin, whose sacrifice fly in the sixth scored Andrew McCutchen to give Pittsburgh a 3-2 lead off off St. Louis starter Joe Kelly, followed Alvarez with another run-scoring single in the eighth.

Marlon Byrd, whose one-out double had moved McCutchen to third base in the sixth, accounted for Pittsburgh's first two runs with a two-out, two-run single in the first.

The Cardinals tied the game in the fifth on a two-run single from hot-hitting Beltran off Pirates starter Francisco Liriano.

The Pirates, who have beaten NL Central rivals St. Louis in eight of 11 meetings this season at PNC Park, want to end the series on Monday rather than have to go back to St. Louis for a Game 5.

"The crowd really gives us a lot of energy out there," Martin said.

"If we keep winning, they're going to keep bringing it. So we've got to keep doing that."

Said McCutchen: "We want to be that team to win. We want to do it at home."

Cardinals manager Mike Matheny expected to see his team rebound from the loss.

"I've been very impressed with how our club has bounced back," the St. Louis skipper said.

"We've got a short memory, but right now it hurts."