Daisuke Matsuzaka worked out at YafuOku Dome on August 29. He felt fine a day after his last outing (no problems with his shoulder, no general tightness) and is currently slated to make his next outing during a Ni-gun Inter-league game against the Yomiuri Giants on September 4. He is expected to start the game and pitch four to five innings. There is still a chance he could make the active roster before the end of the regular season. A lot will depend on what happens over the next two to three weeks.
Source: Nikkan Sports 8/29/2016
[UPDATE 8/31 @ 12:06am]
Nikkan Sports believes Matsuzaka could get two more Sunday Ni-gun starts after his next game on September 4. Assuming no setbacks, he could be ready to make the active roster in time for a Seibu game at Seibu Prince Dome on September 25.
Source: Nikkan Sports 8/31/2016