However, manager Bobby Valentine is skeptical that Dice-K will be ready to join Boston's rotation at that point. If that is the case, look for the Red Sox to get creative and find a way for Matsuzaka to keep tuning up once the official rehab clock runs out.
Matsuzaka, who had Tommy John surgery last season, is scheduled to start for Triple-A Pawtucket on Thursday and then again on May 22.
"Right now, I don't think he's all that close to pitching in the Major Leagues," said Valentine. "He might take a big step, [but] not until he's ready. It's not the calendar that's going to dictate whether a guy pitches in the Major Leagues, I don't think."
The problems Matsuzaka is having seem to be mostly mechanical.
"There's a lot of things that you do before you're totally ready, and I'm not sure he's put his elbow situation behind him yet," Valentine said. "I don't think he totally understands where he is with his elbow."
Essentially, Matsuzaka developed some bad habits while pitching through elbow pain last year, so now he's trying to regain his feel again.
"It's just the understanding of why it happened and what he did to pitch while it was hurt, that mechanic, whether or not that mechanic is something he should be using now or if he should go back to the mechanic he was using when he hurt it," Valentine said. "It's a very confusing state. Until he figures that out totally in his mind, competition is going to be confused. He won't be into the competition. We want him to be here, not only to be healthy, but we want him to be in the competition."