If Morales can recover well enough, he will resume throwing on Tuesday, but it could be a while before he gets back into a game.
The Red Sox stopped the clock on his 30-day rehab assignment.
Morales had left shoulder woes for the latter part of 2012, ending his season early. Is it all related?
"Based on the location of the current injury, you would say no," said manager John Farrell. "But the fact is, it's still on his throwing side, so I can't say they're completely unrelated, but it was a shoulder issue at the end of last year, it's a pec muscle right now. Just looking at that, they aren't related. The fact is, it affects him when he throws, so we're in the situation we are."
Farrell is hoping to get Morales stretched out as a starter to give the team additional depth in the rotation.
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, and follow him on Twitter @IanMBrowne. Jason Mastrodonato is a reporter for MLB.com. Follow him on Twitter @jmastrodonato. This story was not subject to the approval of Major League Baseball or its clubs.