Pineiro underwent an MRI exam on Monday, and the results revealed that he has inflammation in the latissimus dorsi, just below his right shoulder. All areas of the actual joint were cleared in the exam.
"It's just a little bit of inflammation where the lat and the back of the shoulder connect," Pineiro said on Tuesday. "It's a positive thing, because the MRI showed negative. Shoulder, labrum, everything is fine. It's just bad inflammation in there."
Still, Pineiro will not pick up a baseball until Friday, meaning he will miss at least two turns in the rotation. His scheduled Wednesday start will be taken by Anthony Reyes, who was pushed back due to a bout with illness.
Pineiro's next start would almost certainly not come until after the Cardinals' off-day next Tuesday. That puts his availability for the start of the season somewhat in doubt, according to pitching coach Dave Duncan.
"I was told this morning that he's going to be a few days before he picks up a baseball," Duncan said on Tuesday morning. "Until [Friday], he's not going to pick up a baseball. ... I'm not assuming that he'll be there for Opening Day. I'm assuming he will not be there, until he starts throwing again and shows me he will be ready for Opening Day."
That leaves the Cardinals with five pitchers still available from their seven-man mix at the start of the spring. Matt Clement has also been slowed due to an early lack of arm strength.
Adam Wainwright and Braden Looper have been on schedule and are slotted for two spots in the rotation. Pineiro has also been slated for a job, with a three-man competition for the final two positions. Todd Wellemeyer, Reyes and Brad Thompson are battling for the Nos. 4 and 5 spots.
Thompson and Wellemeyer are pitching on the same day, though, so the club only has starters on turn for four out of five days. Looper will pitch on Thursday, and the Cardinals have no scheduled starter for Friday against the Dodgers in Vero Beach, Fla. Wainwright will take his turn on Saturday.
Prospect Clayton Mortensen will get a shot to pitch on Friday, though he is not being seriously considered for the rotation.
"There's nobody else available that's considered a starter," Duncan said. "It would be nice if it worked out where [Kyle] McClellan was available or [Mike] Parisi that day. But they won't be."
Though McClellan and Parisi will not be able to take the open turn this week, both are in the mix for a shot at starting for the big league team coming out of camp.
"They still are candidates," Duncan said.
But the hope is that Pineiro will be able and ready to pitch. It's the second time the right-hander has come down with discomfort this spring.
Three days before his first scheduled start, Pineiro encountered difficulty getting loose while he was throwing off a mound. He was scratched from that start, held out for one start and took his turn for what would have been his second scheduled start.
Pineiro pitched well against the Dodgers on Friday, but on Saturday, he didn't feel quite right. He got only 10 pitches into a Sunday bullpen session before shutting it down.
"It was crazy, because I was good to pitch," he said. "I went through my whole routine, everything fine. That night, it just felt like regular soreness. I thought, 'I haven't pitched in four months, that's why.' Then I tried to go out and throw my bullpen, and it was like I couldn't put anything on the ball."
Matthew Leach is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.