The team is cautious about rushing back last year's NL Cy Young winner. Manager Tony La Russa said 24-year-old rookie Anthony Reyes, who was scheduled to start against the Astros in Carpenter's spot on Tuesday night, would likely stay with the Cardinals until the team is sure Carpenter is ready to return.
Center fielder Jim Edmonds, meanwhile, missed his fourth straight start with what the team called lower abdominal discomfort. Edmonds underwent an MRI earlier Tuesday and was scheduled to meet with a specialist on Wednesday.
"I'm not frustrated," Edmonds said after the Cardinals lost 6-3 to the Astros. "It's one of those things that's not common."
Carpenter, 4-2 with a 2.63 ERA, was placed on the DL retroactive to May 22, the day after Reyes, who replaced him at Kansas City on May 20, was optioned back to the minors. He threw a lengthy bullpen session about four hours before Tuesday night's game against Houston in his first extended workout since the injury and felt no pain.
"I felt good," Carpenter said. "Now we'll see how it feels tomorrow when I wake up."
Carpenter is scheduled to throw again on Friday, and barring problems he'll be slotted back into the rotation. Carpenter thought he'd pitch either Monday or Tuesday.
But La Russa said it could also be later in the week if the team felt Carpenter needed more time.
"We just want to make sure we're not pushing him," La Russa said. "We want to make sure he's ready to take the mound.
"We want to get him back and keep him back, that's the No. 1 criteria. Whenever that is," he said.
Carpenter did not hold back in his bullpen session, saying he did more than he had been expecting with the number of pitches, the velocity and the variety.
"If I recover fine, then Friday I'll get into a more game-type situation and get ready to go," Carpenter said. "I was hoping I didn't feel anything and I didn't feel anything."
Carpenter said he began feeling pain two starts ago and that it intensified in Kansas City on May 19, his last outing in which he gave up six runs in six innings. Carpenter said he found himself changing arm slots in that game in an effort to "find a spot where it wasn't going to be sore."
"It was just at a point where I knew that it was getting worse and not better, and I had to take care of it," Carpenter said.
Carpenter said he felt good enough that he could have pitched Tuesday instead of Reyes, making his third major-league start. But he saw the wisdom of trying to be healthy for the long haul.
Team trainers have told him the pain is not likely to return.
"I could have thrown tonight, no question about it," Carpenter said. "Being May, it's a smart decision. I miss two starts and I'll be ready to go again."
La Russa said it would have been a "crazy risk" to allow Carpenter to pitch on Tuesday.