ST. LOUIS -- The Giants proved Friday night that accomplishing the improbable must be done in improbable fashion.

A pitcher with a losing record as a Giant who was a reject in their last postseason trip preserved their season. The eighth-place occupant in the batting order recorded the game's biggest hit. And an opponent that seemingly possessed insurmountable momentum looked helpless.

The Giants relied on a four-run fourth inning and Barry Zito's masterly 7 2/3-inning effort to stun the St. Louis Cardinals, 5-0, in Game 5 of the National League Championship Series. Brandon Crawford's two-run single and Zito's run-scoring bunt single highlighted San Francisco's uprising in the fourth.

With the baseball world assuming that the Cardinals would eliminate San Francisco and advance to the World Series in an attempt to defend their title, the Giants instead launched their bid to join the short list of teams to overcome a 3-1 deficit in a best-of-seven LCS. Of the 33 previous teams to build a 3-1 advantage in an LCS, 27 proceeded to the Fall Classic.

"I hope you guys enjoy the games," right fielder Hunter Pence said. "We love to play them."

By trimming St. Louis' series edge to 3-2, the Giants accomplished a significant objective: bringing the NLCS back to San Francisco. Following Saturday's scheduled off-day, the teams will reconvene for Game 6 at AT&T Park on Sunday afternoon.

"San Francisco is a great city, but I wish we weren't going back," Cardinals third baseman David Freese said.

Climbing out of a 2-0 hole to defeat Cincinnati in the Division Series emboldened the Giants and prepared them for their current challenge against the Cardinals.

"We all kind of feel like we've been in this situation before," said right-hander Ryan Vogelsong, San Francisco's Game 6 starter. "We're just going to play hard until the end and see what happens."

The end was postponed for the Giants by Zito, who's 58-69 during his six San Francisco seasons and was omitted from the active roster for the entire 2010 postseason. Benefiting from scintillating defense and his own guts, he yielded six hits and weathered early threats by holding the Cardinals hitless in six at-bats with runners in scoring position.

Including the regular season, the Giants have won the last 13 games started by Zito, who tamed a lineup that led the NL with a .276 batting average against left-handers such as himself. He also ignored the expectant red-clad crowd that filled Busch Stadium, eager to toast St. Louis' 19th NL pennant.

"If you get too caught up in the hype and everything else, things get erratic out there," Zito said. "I was focused on slowing everything down. ... I was living pitch to pitch, moment to moment."

It could be suggested that this game alone justified Zito's seven-year, $126 million contract, which made him an object of scorn among the media and many Giants fans during his struggles on the mound. But, as Giants manager Bruce Bochy observed, "He's always been a standup guy with everything."

That included standing up to the Cardinals. Zito's biggest escape occurred in the second inning, when he coaxed opposing pitcher Lance Lynn's double-play grounder with the bases loaded and one out.

"I think that kind of gave us a little momentum right there," Crawford said.

The Giants soon grabbed that momentum for good. As he did in Game 1, Lynn no-hit the Giants for three innings before crumbling in the fourth.

Marco Scutaro and Pablo Sandoval, who played with a painful right foot after fouling a pitch off it in the first inning, singled to open the rally. After Buster Posey struck out, Pence hit a comebacker to Lynn, who flung a throw to second base that caromed off the bag and flew into center field. Scutaro scored while Sandoval went to third base.

"I turned to throw it and I just threw it in the ground," Lynn said. "It was a bad play. I make a good throw there and I'm out of the inning. It was just one of those times where I short-armed it a little bit."

One out later, Lynn walked Gregor Blanco to load the bases. Crawford worked the count to 3-2 before grounding a curveball up the middle, delivering Sandoval and Pence. Zito then pushed a bunt up the grass paralleling the third-base line and beat Freese's throw to first as Blanco charged home.

Zito attributed his execution to extensive practice with third-base coach Tim Flannery, the Giants' bunting guru.

"I knew I didn't have much of a chance hitting off Lynn," Zito said. "But I saw a situation where I could possibly get one down and get another run in, so I tried it."

Sandoval added an eighth-inning leadoff homer off Mitchell Boggs. It was Sandoval's second round-tripper in two nights and his third of the postseason. He hit only 12 regular-season homers.

"You get to the postseason and you see the things you did wrong during the season and all the things you do well," Sandoval said. "You have to keep focused on the things you do well."

That reflected the Giants' collective approach.