"The fact that he's actually on the field is exciting," La Russa said. "We've only seen this how many times? You can count it on less than two hands how many times in the last two years we've actually seen him facing a hitter. So this is a big day, and a fun day."

Though he struggled at times with the location of his fastball, Carpenter snapped off several strong breaking balls.

"My arm felt great," Carpenter said. "My location was off a bit at the beginning, but I felt like the last 10 or so (pitches) I was hitting my spot pretty good. It was just fun to get back out there and be a part of it."

Carpenter won the Cy Young Award in 2005, when he went 21-5 with a 2.83 ERA. He won 15 games for the Cardinals during their 2006 World Series title run but has started only four games since.

He was the opening-day starter in 2007, but left that game with an elbow injury that required Tommy John surgery. Carpenter didn't return to the majors until late July of last season, then left his Aug. 10 start against the Chicago Cubs with what turned out to be nerve-related damage in his shoulder.

He made a relief appearance at Arizona on Sept. 2 and was shut down after the outing because his shoulder was still bothering him. He had elbow surgery in November.

"It looked like he had plenty of arm strength and he looked strong," said general manager John Mozeliak, who watched the session from the side of the batting cage.