JUPITER, Fla. -- Cardinals ace Chris Carpenter won't start Opening Day after a setback in his recovery from a bulging disk in his neck.
The right-hander returned to St. Louis on Tuesday for tests. He threw live batting practice Sunday but didn't feel right the next day.
"He looked really good and felt good; the next day he just didn't respond like we had hoped," manager Mike Matheny said Wednesday. "His shoulder is just not responding and they're uncertain of the root of it. That's what they're trying to get to with tests on the neck and shoulder and trying to figure out where it's all coming from."
Kyle Lohse will start April 4 at Miami in his place. Lohse was 14-8 with a 3.39 ERA last season, leading the Cardinals in wins and ERA.
"It's an honor," Lohse said. "But it comes meaning that Carp's not available -- that's the tough part about it. I wish it were under different circumstances, but I'm proud to take the ball on Opening Day."
Righty Lance Lynn, a setup man, will take Carpenter's spot in the rotation. Lynn is 1-0 with a 1.64 ERA in 11 innings this spring. He made his second spring start Monday. The Cardinals now must replace Lynn in the bullpen.
Carpenter, who turns 37 in April, has been limited in workouts since being diagnosed with the bulging disk March 3. The Cardinals had initially planned to limit his spring training work after Carpenter pitched 273 1/3 innings last season -- including playoffs -- the most in baseball.
He had been scheduled to throw more live batting practice Wednesday. Matheny was guardedly optimistic after watching Carpenter throw Sunday, saying his ace looked great but wanting to be sure he woke up the next morning without any issues.
"He was the one trying to keep us all in check and not get too far ahead of himself," Matheny said. "As he finished I mentioned to him, 'I hope you feel as good as you look because you look really good.' That's what all of us saw. You can tell there's a little bit of hesitancy with him just not knowing how he would respond and that's what happened."
Carpenter has had nerve-related issues that ended his 2004 and 2008 seasons prematurely. They resurfaced in 2010.
"He's been fighting different things for a long time," Matheny said. "He's just so tough mentally; he's so tough physically. He just keeps fighting. This is another setback he's going to answer the bell, too. He always has in the past."