Milwaukee made four errors that led to three unearned runs, and the Cardinals' bullpen pitched brilliantly again to survive an early exit by Jaime Garcia in a 7-1 victory Friday night that gave St. Louis a 3-2 NL championship series lead.
The wild-card Cardinals have two tries in Milwaukee to return to the World Series for the first time since 2006.
"It's a nice win," St. Louis general manager John Mozeliak said. "But we need one more."
Yadier Molina and Matt Holliday had three hits each for St. Louis, which burst to a 3-0 lead in the second when Molina doubled in a run and third baseman Jerry Hairston Jr. allowed Garcia's grounder to go through his legs. Holliday capped the scoring with a two-run double in the eighth.
"We can play better than we have," said Zack Greinke, who took the loss. "And I'm sure we will."
Weeks had committed the Brewers' only two errors in the first four games of the series.
"It's definitely not focus," Brewers manager Ron Roenicke said. "These games, we do have them once in a while. We had one a couple days ago. I'm confident we'll play a good game on Sunday."
St. Louis can wrap up the best-of-seven series and its 18th NL pennant then. Edwin Jackson goes for the Cardinals against Shaun Marcum in a rematch of pitchers from Game 2, won by St. Louis 12-3 as neither starter received a decision.
"I haven't really analyzed it. I try and stay in the moment, bro," Prince Fielder said. "I'm not really looking back or forward, just trying to stay game to game. We have to win both of them, but we've got to win first."
The NL winner hosts the World Series opener against Detroit or Texas on Wednesday.
"We're having a good series right now and, hopefully, we can do it for one more game," Molina said.
Led by Jason Motte, the Cardinals' fifth closer of the season, the St. Louis bullpen is 2-0 with a 1.66 ERA in 22 2/3 innings in the series. St. Louis starters are 1-2 with a 6.04 ERA.
Only one St. Louis starter has lasted long enough to qualify for a victory, with Chris Carpenter working five innings in Game 3. The previous team to have a starter not pitch into the sixth in the first five games of a postseason series was the 1984 San Diego Padres in the World Series, according to STATS LLC.
"We're just trying to win," Holliday said. "If the spot calls for it, our bullpen's been incredible," Holliday said. "They're really fit into roles and it's been fun to watch."
The Cardinals have won 14 straight games on getaway days, a run that began on Aug. 7 at Florida. The win gave players another opportunity to chant "Happy Flight! Happy Flight!"
Milwaukee had not made more than three errors in a game during the regular season, but the Brewers' sloppiness reached a near-record level. Milwaukee was one shy of the LCS record for errors in a game, shared by the 1974 Los Angeles Dodgers and 1976 New York Yankees, according to STATS LLC.
"You've taken so many ground balls your whole life, you know what a ground ball is going to do," Hairston said. "And then when it just shoots down and scoots and once it hits that lip, it's just shock."
Cardinals manager Tony La Russa had a quick hook once again. Garcia opened with four scoreless innings, then allowed three hits and a sacrifice in a span of four at-bats in the fifth as Corey Hart singled in a run. With two and on and two outs, Octavio Dotel relieved and struck out Braun.
"There's a lot of conversation about Game 1 and how quickly they put some runs on the board," La Russa said.
Garcia was understanding.
"He's been doing this for so long and he's been so successful and he's got his reasons," the pitcher said.
Dotel (1-0) struck out two in 1 1/3 hitless innings, combining with three other relievers for 4 1/3 innings of scoreless, two-hit relief. Motte got four outs for his second save of the series,
"I'm just out there doing my thing," Motte said.
With Milwaukee down 5-1 and trying to rally with two on and two outs in the eighth, lefty Marc Rzepczynski relieved and struck out Fielder. Against Rzepczynski, Fielder is 0 for 4 with four strikeouts and two walks.
"With two strikes I said I'm just going to bounce at it and see if he swing," Rzepczynski said. "And today, he did."
Greinke left pitches over the plate in some key spots and allowed five runs -- just two earned -- and seven hits in 5 2/3 innings with no strikeouts and two walks.
"I made several mistakes that ended up costing us," Greinke said. "I definitely could have done better and made it a better game."
St. Louis had been hitless in 15 at-bats with runners in scoring position -- and 22 at-bats with runners on base -- before Molina's RBI double off the right-field fence. Hart just missed on a leaping attempt at the right field fence.
Hairston saved at least one run at third base with a spectacular diving catch to his left on Nick Punto's low liner for the second out. But when he botched Garcia's easy grounder, St. Louis was up 3-0.
Garcia's RBI groundout made it 4-0 in he fourth, the first RBI by a Cardinals pitcher in the postseason since Jeff Suppan homered in the 2006 NLCS against the Mets.
Albert Pujols had an RBI single in the sixth to chase Greinke.
Now it's on to Milwaukee, where the Brewers were a major league-best 57-24 at home during the regular season.
"They're really tough up there in their ballpark," Lance Berkman said. "It's certainly more feasible for us to have to win one of two than to win both."
Braun doubled in the first and has reached base safely in the opening inning of nine straight games, going 7 for 7 with a walk and hit by pitch. He has 22 hits in the postseason, matching the franchise record by Paul Molitor and Robin Yount. ... Chuck Berry, a St. Louis musical icon, performed the national anthem with his daughter, Ingrid. Wearing his trademark sailor's cap and a No. 84 Cardinals jersey (his age), Berry mostly watched and threw in occasional harmony. ... Cardinals Hall of Famer Ozzie Smith threw a one-hop first pitch with injured St. Louis starter Adam Wainwright on the receiving end for the third straight night.