"We've got an opportunity to keep his arm moving, keep him in shape," said manager John Farrell. "He'll stretch a little bit with long toss today and the plan is for him to throw a bullpen [session] tomorrow, without a glove. The precaution we have to take right now is making sure he doesn't perspire too much that may cause bacteria or whatever to get into the incision that's still closing up."
It is still too early to know if Peavy will return in time for the start of the regular season.
"Again, the next three days will probably have a lot to do with when he gets to the mound next in a game," said Farrell.
If Peavy starts the season on the disabled list, Farrell said that Chris Capuano or Brandon Workman would be the two most likely candidates to fill in.
Capuano makes his debut in a Boston uniform on Wednesday in Jupiter, Fla., against the Cardinals.
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, and follow him on Twitter @IanMBrowne. This story was not subject to the approval of Major League Baseball or its clubs.