Thanks to the satellite system the Red Sox use to track all their Minor League affiliates, manager Terry Francona was able to watch Matsuzaka's performance.
Over 37 pitches, Matsuzaka allowed one hit and no runs, walking none and striking out four.
"Everything was pretty good," said Francona. "Good breaking ball. He commanded his fastball. He stayed down. Threw some good changeups. It was generally really positive."
Matsuzaka will report to Fenway Park on Tuesday to meet with Francona and pitching coach John Farrell. Matsuzaka's next step will be a start for Double-A Portland on Saturday, followed by an outing with Triple-A Pawtucket on Sept. 3.
Assuming all goes well, Matsuzaka could be activated by the Red Sox on Sept. 8.
"By then, he certainly wouldn't be stretched out enough to go deep into a game," said Francona said. "Saying that, there may not be a game for him to pitch anywhere in the Minor Leagues. If Double-A [Portland] doesn't make the playoffs, there's nowhere for him to pitch. So being in September, depending on what our situation is, if he's throwing the ball well but isn't completely stretched out, we can make that work a heck of a lot better than we could in July or August."
The Red Sox have been pleased with the work Matsuzaka has done on his thorough rehab program, which started on June 21, when he was placed on the disabled list with a mild right shoulder strain.
All along, the Red Sox were more concerned with Matsuzaka getting his entire arsenal back instead of having him make a speedy return.
"He's done a phenomenal job," said Francona. "Just getting him back at full strength, [having him be] Dice-K will be very welcome. And I think we probably needed to do this. Sometimes you have to butt heads. However you get there, getting there is what's important. I think we've done that."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.