Manager Buck Showalter confirmed that Britton, who dazzled in spring training, will make Sunday's start. And president of baseball operations Andy MacPhail estimated that Matusz could miss anywhere from three to six weeks.
"With the duration that we think Brian's going to be out, we're going to need the fifth starter, so we may as well plug in Zach now as opposed to waiting till the ninth or 10th," MacPhail said.
The initial plan called for Britton to stay down until at least April 21, so the Orioles would gain an extra year of service time and allow him to work on his secondary pitches. But Matusz's back issue created a change in thinking.
"Sometimes, fates just don't allow it and you've just got to do what you've got to do," MacPhail said. "We thought we had five starters and Zach would be six and Justin (Duchscherer) would be seven, but unfortunately we lost one before we threw a pitch, so we just have to adjust. In my view, Chris' day is tomorrow. He can pitch tomorrow. And Zach is eligible to pitch on Sunday. We can sort of keep things in line.
"The kid had a good spring and deserves the opportunity. And as the season evolves, we'll just see how everybody does."