Colon, pitching at Scranton, lasted just two-thirds of an inning, giving up four hits and three runs, walking one and striking out one. He threw 32 pitches, 18 of which were for strikes.
For Colon, this rehab assignment will be anything but a sprint. Manager Terry Francona indicated that even before the right-hander's unsuccessful first step.
"It's almost like you're going through Spring Training again knowing you're down for a period of time," Francona said. "If you let him go out and throw three [innings], any pitcher is going to feel it more than you want to. We've got to build him back up again. I think he will build up quicker, but we still have to go through that process."
What is the minimum amount of starts Colon will need at Pawtucket?
"It would be hard to imagine him not having, probably four," Francona said. "You look at two [innings], [then] three, four, five. You always figure one in there where the guy goes backwards a little bit or needs to go backwards on workload. I think that's realistic."
Reliever David Aardsma -- placed on the disabled list on July 19 with a right groin strain -- also pitched for Pawtucket on Tuesday, walking two but allowing no hits over an inning. Aardsma threw 21 pitches - nine for strikes.
Before Aardsma's outing on Tuesday, Francona said that the right-hander could be on track to join the Sox for their four-game weekend series in Chicago, which begins on Friday.
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.