Simulating two innings, Colon threw 21 pitches in the first inning and 22 pitches in the second frame to four Sox Minor Leaguers. General manager Theo Epstein and pitching coach John Farrell observed from behind the batting catch, while Triple-A Pawtucket pitching coach Rich Sauveur monitored from behind the mound.
"I think the most important thing was getting loose," said Farrell, who noted that Colon had no issues in between innings. "We'll just make sure that tomorrow he feels fine and we'll look to slot him into a game at some point this coming week."
Depending on how Colon responds Monday, Farrell expects Colon to appear in a Spring Training game Thursday, likely not more than two innings or 30 pitches.
"If it is an inning, it might be 20-25 pitches," Farrell said. "But you could also see him going through an inning fairly quickly, because he locates the ball. That's the one thing in all of his bullpens -- his command of the baseball has been very good, particularly with the four- and two-seam fastballs."
Farrell said Colon threw his entire repertoire -- four- and two-seam fastballs, breaking balls and changeups -- during the session.
"The one key on his changeup -- certainly there's a tendency to slow his body down a hair, but that's more just getting closer to season form and the aggressiveness in his delivery," said Farrell.
Colon, speaking through Eddie Romero Jr., Boston's Latin American operations coordinator, said he is pleased with the progression of his work this spring and the ability to replicate game conditions.
"He says he feels really good and he was very pleased with his control more than anything," Romero said.
"He says he feels even better. It wasn't so much different, because he always simulates game situations, but he did like the fact that there was somebody in the cage there to really give him more game-like [conditions].
"He says he feels very good right now, where he is right now. He also feels that the staff has brought him along at a very nice pace, so he's very comfortable with the work that they've given him up until now."
Colon, who cited his control and velocity as factors he's particularly pleased with, said he's not surprised at the rate of his progress this spring.
"He says he kind of expected this because he was working hard in the Dominican before he came over to Fort Myers," Romero noted. "And he says he's kind of right where he expected himself to be.
"Absolutely, he feels better than ever. He feels he's in good shape and his arm feels really healthy."
While Colon is still working on his overall performance, he's looking forward to getting into a game so he can work on his breaking pitches.
"Really, more than anything, the execution of his breaking pitches," Romero relayed. "He thinks that will be the most important thing once he gets into game activity."
Maureen Mullen is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.