"It's huge," Carpenter said afterward, the top of his right hand still bloodied. "We needed this game badly. To do it in that kind of fashion, hopefully that will get us on some kind of roll."
Not only did the Cardinals, who had lost three straight, need to initiate their own momentum, but they needed to stop Milwaukee's. Allen Craig's two-out RBI single off Brewers reliever Kameron Loe in the 10th assured the club of both.
The victory prevented a sweep, as well as additional upward movement by the Brewers in the standings. Milwaukee, which has won 15 of its last 20 games, had closed to within five games of the Cardinals for the league's second Wild Card spot.
While it was unlikely to think that the underachieving National League Central club would rally to catch St. Louis by the end of the season, the Cardinals understand better than anyone that anything is possible. On this date a year ago, it was the eventual World Series champs who sat 7 1/2 games out of a playoff spot.
"We obviously didn't do as well as we thought we could have," Craig said of series. "But it was good to finish strong."
"I'm OK with the three games we just played -- we played great," Brewers manager Ron Roenicke added. "We lose today, shoot, that's a great team we're playing, and we played a really good game today. They came through with a big hit."
The Brewers came up with the big hit first. With two outs and two strikes against Cardinals closer Jason Motte in the ninth, Brewers outfielder Norichika Aoki poked a two-run homer narrowly over the short porch in right field.
That cost Motte his 34th save and the Cardinals the lead. The inning ended with the game tied at 4.
"I was trying to go away," Motte said. "I don't know if it cut back or I pulled it back, but it ended up on the inside corner. But with his type of swing, that ball was right down the middle for him."
It took until the 10th, but the Cardinals answered back.
Carpenter reached on a one-out single and advanced to second on a wild pitch as pinch-hitter Adron Chambers struck out. With two out, Craig, hitless in his first four at-bats, laced a single to right. Aoki had a play at home, but Carpenter, seeing the play unfold in front of him, swiftly dove around Lucroy.
"That would have been a long, long flight," manager Mike Matheny said, "if we didn't pull that off."
Instead, it's a happy flight, as the Cardinals head west for a seven-game road swing knowing that they remain in playoff position.
"Winning walk-offs like that are special," starter Joe Kelly said. "Hopefully we can carry off the momentum to LA and San Diego."
Motte's blown save cost Kelly a chance to pick up his third win in his last four starts. However, there was little else not to like about the right-hander's afternoon.
Sticking with a focus of throwing down in the zone to try and induce groundball outs, Kelly handed a 4-2 lead to the bullpen after six innings. He allowed lone runs in the second and fourth, both coming with two out. After the latter, he wrapped up his start by retiring seven of the last eight batters he faced.
"Six innings is all you can ask for," Matheny said. "He's been obviously a pleasant surprise throughout the season for us. He continues to make adjustments. That's something he does well. He can adjust to being a groundball pitcher or someone who tries to strike somebody out."
The Cardinals built up a lead for Kelly quickly. Matt Holliday tagged Brewers starter Shaun Marcum for a two-run, first-inning homer. Two batters later, Carlos Beltran followed with a first-pitch blast of his own.
While Beltran still leads the team in home runs -- he now has 28 -- the long ball was a welcome distraction from his recent offensive woes. Admittedly still bothered by left hand discomfort and an achy left knee, Beltran entered the day with a home run drought extending 23 games in length. He had hit .141 and driven in just five runs during that span.
Beltran added an eighth-inning single to seal just his second multi-hit game since Aug. 10.
"For me, the last thing I'm worried about is homers," Beltran said. "I'm more worried with having quality at-bats. Homers, when you have quality at-bats, will come. Lately, for me, it's been a battle at the plate. It was a good day for me to go out there and get a couple hits."
The Cardinals added their fourth run with a two-out RBI single from Carpenter in the second. Carpenter has driven in eight in his last eight games. He improved to 10-for-21 with runners in scoring position and two outs on the year.
"Spark is the right word," Matheny said of Carpenter's presence. "He's absolutely hard not to have in there."
Before Motte's brief implosion, Edward Mujica and Mitchell Boggs worked around trouble to preserve the two-run lead. Lance Lynn earned the win by pitching a scoreless 10th.