Ludwick's fifth home run in four games came against Jason Johnson, a starter called into duty, and rescued a Cardinals bullpen that wasted a four-run cushion in the ninth for its major league-leading 27th blown save. The latest failure could cost Jason Isringhausen, recently restored to the closer role, his job.
"We've had some heartbreaking losses," manager Tony La Russa said. "If we'd have lost that one it would have been high up there. When you can just taste that win, those are the toughest, and we'll see in the next few days how much it means to us."
Adam Kennedy singled for his third hit to start the inning and Pujols popped up against Johnson (1-1) before Ludwick lofted a 2-1 pitch over the center-field wall for his third career game-ending homer, and first since May 17 against the Rays.
Ludwick is batting .469 (15-for-32) with five homers during an eight-game hitting streak that has hiked his average to .303.
"I'm just trying to get good pitches to hit and drive them," Ludwick said. "Tonight, up until that at-bat, I don't think I did a real good job. I'm just glad I could contribute a little bit."
Jaime Garcia (1-1) pitched a scoreless 11th for the Cardinals.
Johnson (1-1) got one out two days after throwing 87 pitches over 4 1/3 innings in a 9-3 victory over the Diamondbacks. The Dodgers used five relievers and had two left, but manager Joe Torre was saving closer Jonathan Broxton and Hong-Chih Kuo was unavailable after pitching five times in eight days.
"They asked me to go out there, I'll go out there," Johnson said. "It's the big leagues, you know."
Both teams missed chances to end it earlier. The Dodgers stranded five runners and the Cardinals four in the ninth and 10th.
Manny Ramirez, the 2004 World Series MVP in Boston's sweep of St. Louis, was booed before each of his at-bats. He didn't seem to mind, going 2-for-3 with a pair of singles and trotting home with the tying run in the ninth on Casey Blake's sacrifice fly.
Ramirez also drew an intentional walk to load the bases with two outs in the 10th before left fielder Joe Mather made a nice running catch on James Loney's sinking liner. Ramirez is 10-for-16 with two homers and five RBIs in four games since joining the Dodgers at the trade deadline, and is a .372 career hitter (16-for-43) against the Cardinals with three homers and nine RBIs.
Chris Carpenter, the 2005 NL Cy Young Award winner, threw five economical innings in his second start of the season for St. Louis. He allowed only three singles and needed just 51 pitches in an outing likely shortened by a pair of rain delays totaling 1 hour, 5 minutes and separated by only two at-bats in the bottom of the fifth and top of sixth.
"I don't think he can repeat that the rest of the year but that was vintage," La Russa said. "But I just don't think in his second start you can have a rain delay after five innings and send him back out."
The Dodgers trailed 4-0 going into the ninth, and hadn't put a runner in scoring position in the first eight innings.
Isringhausen, returned to the closer's job last week, relieved Villone. Isringhausen got the first out but then gave up four hits and a walk in a span of five at-bats. Isringhausen had one bad break on Loney's bases-loaded infield hit, a slow roller down the first-base line that the pitcher couldn't field.
"But there was no doubt they got some base hits before and after that," La Russa said. "I guarantee you there's nobody more disappointed than Izzy."
General manager John Mozeliak said he'd "strategize" with La Russa and pitching coach Dave Duncan on Wednesday "and see what makes the most sense."
"But you can't just keep giving games away like that," Mozeliak said. "We're very supportive of Izzy and we've stood by him, but at some point we've got to get some results."
Isringhausen, seven saves shy of 300 but with seven blown saves in 19 chances and a 6.28 ERA this year, declined to speak to reporters.
Pujols, who snapped an 0-for-13 slump with a single in the first, hit a two-run drive off Chan Ho Park to give St. Louis a 4-0 lead in the seventh. It was his 22nd of the season.
Chad Billingsley, coming off his first career shutout, also worked five innings for the Dodgers and allowed a run and six hits.
After the game, the Cardinals announced they had signed infielder Felipe Lopez, released last week by the Nationals. ... Jones' third homer was his first since May 15 at Milwaukee and the 371st of his career, breaking a tie with Gil Hodges for 66th on the list. ... Carpenter is 8-5 with a 2.00 ERA in 19 career starts at Busch Stadium. ... The Dodgers have lost three straight on the road.