Matusz will make his first start for an affiliate on May 16, according to manager Buck Showalter.
As the plan is currently constructed, Matusz will throw two to three innings tomorrow at Twin Lakes Park and three to four innings in his next start. He'll go at least four innings in his first start with a minor league team.
Shortstop J.J. Hardy will bat second and play shortstop tonight as he begins an injury rehab assignment with Triple-A Norfolk. He's expected to play five or six innings and receive three or four at-bats. It depends how the game unfolds.
Hardy could be activated from the disabled list on Tuesday.
The Orioles haven't decided whether to go back to a 12-man pitching staff when Hardy returns.
Also, Luke Scott will undergo an MRI on his right shoulder on Monday. He's dealing with some soreness, but it's not considered serious. The MRI is viewed as a precaution.
Jake Arrieta will start Tuesday against the Mariners at Camden Yards. The rest of the rotation hasn't been determined, which means the Orioles are discussing whether to skip Chris Tillman on Wednesday.