BALTIMORE-- Orioles rookie Brian Matusz (left triceps bruise) didn't throw on Tuesday, but was optimistic that his injury, suffered in the second at-bat of Monday's win, wouldn't keep him from making his next scheduled start.

Matusz said the area was still a little sore and manager Buck Showalter made it clear following Monday's game that the team would exercise caution in moving forward.

"Normally I would throw every day, but since [the starters are pitching] basically once every seven days it's OK to just take today off and see how it feels [on Wednesday]," Matusz said.

Both Matusz and Showalter didn't think the nature of the injury, which came off Yunel Escobar's comebacker, would force the 23-year-old to be shut down any earlier than anticipated.

"We feel confident that there is nothing structurally wrong there," Showalter said.

"It's just a matter of where we slot him back in. Until he's able to take a work day and be fine with that, there's nothing imminent. But I don't see him, at the worst, taking his normal turn."

Like several of the O's young arms, Matusz has been on a roll as of late. He took a four-game winning streak into Monday's start and was named American League Rookie of the Month in August

"I would like to be able to continue to throw and build my innings up," Matusz said, when asked how he would feel about the O's shutting him down after his injury. "So hopefully that won't come about."

Roberts day-to-day after hit on right knee

BALTIMORE -- Brian Roberts wasn't in Tuesday's starting lineup, as the Orioles second baseman was a late decision for manager Buck Showalter, who waited for Roberts to hit in the cage before making out his lineup card.

Roberts was struck in the right knee by Blue Jays reliever Jason Frasor's pitch in the bottom of the eighth inning of Monday's win, and he did not return for the top of the ninth.

"Robby wanted to stay in there, but I didn't like what I was seeing [from him on the basepaths]," Showalter said postgame of the move, which inserted Robert Andino at second base instead.

Andino got the nod again on Tuesday, with Roberts' availability still day-to-day and with Julio Lugo dealing with chronic sinusitis, which has sidelined him since the weekend. Lugo received an MRI on Tuesday afternoon and will continue to be evaluated going forward, although it has been determined that his condition was not a lingering result of being struck in the head in Anaheim in late August, which was an initial concern.

Although the O's are stretched thin in middle infielders, Showalter said Tuesday that he had conferred with president of baseball operations Andy MacPhail and right now didn't anticipate adding another player to an already-expanded roster.

"With Andino here and [Cesar Izturis] and the versatility of Ty [Wigginton], I think we're in pretty good shape there," Showalter said.