"Everything's good," Marcum said on Saturday, a day after meeting with team doctors to assess the severity of his symptoms.
"I'll take a couple days off and rest it, then pick the throwing program back up Monday or Tuesday. I'll probably just miss a start down here, but nothing during the regular season, as of right now."
2010 Spring Training - null
Sights & Sounds
Spring Training Info
Marcum's fate had the club worried, after already suffering the loss of Opening Day starter Zack Greinke, who injured his ribs in a pickup basketball game, and struggling to find the depth to replace him.
"He's progressing," manager Ron Roenicke said of Marcum. "They moved his shoulder around in the training room and it felt good. I don't know when he's scheduled to throw a bullpen, but it looks like he'll skip just the one start."
Marcum will not do any baseball activities until early next week, though he said the tightness was something he could have pitched through during the regular season.
"Today I feel pretty good," Marcum said. "There's no pain or anything. I think I just got overworked a little early on in Spring Training and got a little fatigued, so we're going to give it a couple days to rest and pick it back up. We'll get back there quick."