Cardinals starting pitcher Jeff Weaver threw five scoreless innings to set up the win in San Diego against the Padres with sluggers Albert Pujols and Jim Edmonds each hitting RBI singles in the fourth inning to secure an eventual 2-0 win.
Weaver, pitching just his second career playoff start, struggled in the first inning but finished strongly allowing just two hits before St Louis brought in their relievers.
Cardinals bullpen pitchers Randy Flores, Josh Kinney and Tyler Johnson then combined to pitch 2 2/3 innings, giving up just one hit before Adam Wainwright took over in the eighth to earn his first career post-season save.
Bruce Bochy, Padres manager, rued his side's missed opportunity in the first inning when Weaver allowed two runners on base with .333 hitter Josh Bard at the plate – with Bard only managing to hit a soft grounder to Pujols at firstbase.
"We had him on the ropes," Bochy said.
"Weaver's the guy who beat us today. We've scored one run in two games. That's not going to work. I felt confident about the offense today but he shut us down.
"We've been very resilient and hopefully we'll show that in St. Louis."
St Louis has now beaten San Diego in eight straight post-season games, including last year’s sweep in the divisional series.
The Cardinals can repeat that sweep performance over the Padres as the best-of-five series moves to St Louis with a game three on Saturday.
Mets beat Dodgers in New York
At Shea Stadium, Tom Glavine also turned in an inspired performance to lead the Mets to a 4-1 win over the Los Angeles Dodgers, and a 2-0 series lead.
40-year-old Glavine pitched six scoreless innings while the Mets scored single runs in the third and fifth innings and added two unearned runs in the sixth.
Mets starter Tom Glavine helped
his side to a 4-1 win in New York
"First and foremost I wanted to enjoy it," said Glavine.
"Tonight was probably the most relaxed I've been the whole year long."
Meanwhile, over in the Bronx, the Mets neighbours the New York Yankees lost game two in their series against the Detroit Tigers, after it had been postponed from Wednesday due to rain.
Once again, the starting pitcher was the star of the show with Tigers right hander Justin Verlander hurling 5 1/3 solid innings, yielding three runs on seven hits, with the Tigers coming back from a 3-1 deficit to win the match 4-3 and tie the series.
"I hope in my heart that everybody realises that we are a playoff team and that we proved that today," Tigers manager Jim Leyland said.
"I hope everybody believes we're worthy to be in the playoffs, because before today not everybody did."
Games three and four will be played in Detroit on Friday and Saturday.