The first thing that will need to happen is either Class A Greenville or Salem would have a playoff game on Wednesday, when Matsuzaka is next scheduled to pitch.
The other thing would be for Tim Wakefield's back to hold up. The knuckleballer was back in the rotation on Saturday, but the last time he made a comeback, he had to get a cortisone shot after his first turn back.
After allowing two runs over 4 1/3 innings at Triple-A Pawtucket, throwing 67 pitches, Matsuzaka rejoined the Red Sox in Chicago before Saturday's game.
Red Sox manager Terry Francona said that the club is keeping its options open with regard to where Matsuzaka pitches next.
"We don't know," Francona said. "And when I say that, it really doesn't matter for the next few days. Regardless of where he pitches, he's got to go through his normal progression for the week. We need to see how Wake comes through today.
"We have the ability, it looks like, to pitch [Matsuzaka] another game somewhere in the Minor Leagues. I think in a perfect world, we'd like him to pitch another game [in the Minors]. We'll see. We'll sit down as a group, which we don't have the ability on a Saturday morning to do, nor is there really any reason to yet."
If Matsuzaka pitches in the Minors on Wednesday, Paul Byrd will pitch that night's game against the Orioles. Byrd sparkled in his return from semiretirement, pitching six shutout innings against the Blue Jays. But he was rocked by the White Sox on Friday night, giving up 10 hits and seven runs over 2 1/3 innings.
Matsuzaka made a step forward from his previous start, when he gave up five runs in a 49-pitch first inning for Double-A Portland.
"I think it was pretty good. He was 89 to 92 [mph]," said Francona. "He gave up a couple of solo homers. For the most part, I think everything was pretty upbeat about it. I'd like to talk to him in person and see. But I think everything was pretty upbeat."
Matsuzaka last pitched for the Red Sox on June 19 before going on his second disabled-list stint of the season because of right shoulder weakness.
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.