FORT LAUDERDALE, Fla. -- The Orioles' prospective rotation plans hit another bump on Monday, when the club learned that John Parrish had a cortisone shot and Rich Hill would need an MRI. Both came through their respective procedures fine, but they may not be back on the mound until late in the week.

And with those two hitting the sidelines, the Orioles are now three veteran arms down from their original equation. Brad Hennessey, who was diagnosed with a sore right elbow last week, won't be back on the mound until this weekend. And if Hill's MRI comes back with a red flag, the Orioles could have to scramble to fill in the blanks.

"I think it's all right," said Hill, who was scratched from his Sunday start with a stiff left elbow. "There's some fluid buildup in there, and it's making the joint not as mobile in flexing and extension. But I'm not discouraged by it, because I threw the day after I started feeling the stiffness in my elbow.

"The ball was coming out fine. I just haven't thrown in a couple days. We'll see what the MRI says."

Hill's availability is imperative for the Orioles, who have made him one of the early favorites to snag one of the three vacant rotation slots. Hennessey was also highly regarded before coming down with elbow pain in his first start, and Parrish may have been a chief contingency plan before struggling with left shoulder inflammation.

Baltimore manager Dave Trembley said before Monday's game vs. the Red Sox that he hopes to have a healthy Hill back soon.

"There was nothing on the X-ray," Trembley said of the initial testing. "The guy's getting the whole kitchen sink and kit-and-kaboodle. They're giving him every conceivable workup possible to rule out everything. The X-ray [showed] nothing. So now they're going to move to an MRI to make sure that's clean as well."

Hill, who was acquired from the Cubs for a player to be named later, could throw Baltimore's rotation plans into flux. If he's unavailable for any extended period of time, the Orioles would have to seriously consider Radhames Liz or Hayden Penn. If that plan doesn't pan out, Baltimore could promote a pitching prospect ahead of schedule.

The Orioles brought 37 pitchers to camp just because of that possibility, and Trembley admitted on Monday that he's been impressed by prospects like Brian Matusz, Brad Bergesen, who hurled three shutout innings against the Red Sox on Monday, Jake Arrieta and Chris Tillman.

"I think that becomes a little clearer after they go the second time," Trembley said. "I think that's what we're in right now. We've got to see Penn again, see where he's at. You know, obviously, Matusz is not going to make the team. Let's be honest there. But he's been very impressive. I think there are some candidates that will step up."

Baltimore will stage an intrasquad practice on Tuesday, and Trembley said he believes the team still has a surplus of arms. And with some of the veterans on the mend, he knows he can count on the prospects to fill the gap. Consequently, he may also show some of the older players that their rope is getting thinner.

"I think it sends a message to the other guys: The cavalry's coming," Trembley said. "There's guys on the way, and they're going to get here quickly. Competition's a wonderful thing. Those guys are going to be here. I'm convinced of it."