Red Sox manager Terry Francona revealed that Matsuzaka, who will throw a side session at Tropicana Field on Saturday, will likely begin his Minor League rehab assignment for Triple-A Pawtucket on Tuesday.
"Dice-K will throw a side [session] tomorrow, about 45 pitches, and then go out and pitch on Tuesday," said Francona. "It's probably [at] Triple-A [Pawtucket], because I think they're home. [He'll] probably [pitch] three innings, 45, 50 [pitches]."
The PawSox are home against Toledo on Tuesday.
Matsuzaka has been on the disabled list since April 15 with a mild right shoulder strain. More than anything, the Red Sox feel that the pitcher was a victim of ramping up too soon for the World Baseball Classic.
The downtime has had the desired effect.
"The idea was to never put a Band-Aid on this," Francona said. "He tested out really well today with all his strength and he is really starting to throw the ball with some velocity, with some arm strength. We're just trying to do the right thing."
Matsuzaka isn't the only Sox player getting ready to embark on a Minor League rehab. First baseman/outfielder Mark Kotsay, who underwent back surgery in late January, will report to Pawtucket on Saturday and should be activated by the Red Sox shortly.
"He had a good workout today [in Boston] and he'll go tomorrow," Francona said. "He'll DH and then play six innings, I believe, [Sunday], in the outfield."
Of course, no Red Sox player will get a more favorable reception at Pawtucket than outfielder Rocco Baldelli, who is also nearing a rehab assignment. Baldelli, placed on the disabled list on April 21 with a left hamstring strain, could DH in a Minor League game by Monday.
Francona wasn't sure yet on the logistics, but given that Baldelli is a native Rhode Islander and still lives there in the offseason, Pawtucket would be a natural fit.
Baldelli never played a Minor League game at McCoy Stadium. This would be his first game there since high school.
"I don't know what the exact plan is, but I'm happy with how I'm feeling. I know it will be sooner rather than later," Baldelli said. "I feel like I can do anything they ask me to do at this point. I've pretty much done everything. No issues. I feel good."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.