Carpenter will return to St. Louis on Wednesday and be evaluated on Thursday. Until then, the Cardinals do not have a timetable for his return, but the early indications were that a stint on the disabled list is likely.
"No matter what happened in the game, the important thing is it looks like he is going to be out for a while," Cardinals manager Tony La Russa said. "That kind of overwhelms everything else that happened in that game. ... I'm not happy. This is a [bad] day. I'm not going to fake it."
The Cardinals snapped a scoreless game with three runs in the top of the fourth inning. Before the bottom of the fourth, Cardinals trainer Barry Weinberg and La Russa were alerted by catcher Yadier Molina and visited Carpenter on the mound after his warmup pitches. He was removed from the game. Carpenter said he injured his rib cage on a swing during his last at-bat.
"I felt it a little bit in that swing and every warmup pitch got worse and worse until it bit pretty good," Carpenter said. "There was nothing I could do about it but come out."
Carpenter is already on the comeback trail. He pitched in just five games in 2007 and 2008 with right elbow and shoulder injuries. This is a different type of injury.
"I have no idea, I have never done it before," Carpenter said. "There's nothing else to say, but I pulled my oblique and there's nothing I can do about it. Go home and find out what's going on, start treating it and get better and get back.
In his 2009 debut, Carpenter threw seven shutout innings while allowing one hit with seven strikeouts.
"I've been through a lot and you never know when something will happen," he said. "I felt as strong tonight as I have all Spring Training. Something like this is part of the game. You deal with it and you move on."
On Tuesday, Carpenter allowed four hits and struck out two batters in the brief outing against the Diamondbacks. He threw 50 pitches, 33 for strikes. Kyle McClellan replaced the right-hander on the mound.
"He feels terrible. He was apologetic," La Russa said. "Every time he gets hurt, [he feels] he lets everybody down. That's why he is so respected."
The Diamondbacks won the game, 7-6, on a single by Eric Byrnes in the 10th inning, but the result of the contest meant little after the game.
"It's a frustrating spot to be in right now, but our hope is that it's not going to be that serious and most importantly, it's not his elbow or shoulder," Cardinals general manager John Mozeliak said. "I think we'll have a better idea of where it is [Wednesday], but I think we are going to contemplate what our needs to be, and try to address that the first thing in the morning.
"I think we know what the likelihood is, but we just want to make sure we are not jumping the gun."
Jesse Sanchez is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.