Working his first complete-game win since Sept. 11, 2006, Carpenter held the Reds to three hits and one run while throwing a 95-pitch gem in a rapid-fire 2 hours, 5 minutes.
Albert Pujols drove in all three runs with a 431-foot, two-run homer and a double, then lined out hard to third base in his last at-bat.
"That's two superstars," manager Tony La Russa said.
La Russa gets to see Pujols every day. Carpenter's availability has been erratic the last three seasons because of various arm injuries, but even though he has missed six weeks with a torn left oblique muscle this season, he is 4-0 with a 0.71 ERA.
"He's so good," La Russa said. "It's a pleasure to watch him. And you miss him so much when he's not pitching."
Carpenter faced just one batter over the minimum. Pujols, who has enjoyed his vantage point since Carpenter joined the team, said, "I've had fun the last seven years watching him do the same thing over and over, whenever he's healthy."
CARDINALS 3, REDS 1: The Cardinals reached the 54-game mark, the one-third point of the season, tied for first place with Milwaukee in the National League Central. RHP Chris Carpenter's first complete game in 2 1/2 years enabled St. Louis to split the four-game series with Cincinnati, even though the Cardinals scored three or fewer runs for the eighth time in their last 11 games.
• RHP Jess Todd, whose contract was purchased from Class AAA Memphis on Thursday, became the 12th rookie to be on the squad this season. Todd, 3-1 with a 2.96 ERA, had 11 saves in the Pacific Coast League. But as a former starter, he likely will be used as a long man with the Cardinals.
• RHP Blaine Boyer, who worked five innings in relief Wednesday, giving up two runs (one earned), was designated for assignment. The Cardinals hope to outright him to Class AAA Memphis, where they want him to start.
• RHP Kyle Lohse probably is headed to the disabled list with a right flexor tendon strain. The injury occurred when he threw awkwardly to first base Wednesday after making a diving attempt at fielding a bunt by Cincinnati RHP Johnny Cueto. The Cardinals are likely to place Lohse on the 15-day disabled list Friday or Saturday and promote either INF Tyler Greene or INF/OF Joe Mather from Class AAA Memphis.
• INF Joe Thurston has been given permission to be gone two or three days to attend the birth of his child.
• RHP Brad Thompson, who pitched strongly for five innings in his first start of the season for the Cardinals on Tuesday, probably will move into the rotation while RHP Kyle Lohse is sidelined with an arm injury.
• RHP Joel Pineiro completed a bullpen session Thursday without incident and is projected for a Sunday start against the Rockies. Pineiro missed his regular turn Wednesday due to lower back spasms. "I'm pretty sure they might be watching the pitch count, but other than that, I see no reason why I can't go out there and do my thing this weekend," Pineiro said.