Uehara tossed a scoreless inning for Double-A Bowie earlier on Thursday, with pitching coach Rick Kranitz on hand for the 13-pitch outing. Manager Dave Trembley said the team wanted Uehara to throw against some better competition before being activated.
"He's ready to go. He'd like to be here now," Trembley said. "But Kranny talked to him after his outing today, and we're going to get him to pitch at least one more time in Triple-A."
It was Uehara's second rehab outing; he also threw a scoreless inning, allowing a hit and a strikeout, for Bowie on Tuesday night. Although both of Uehara's innings have been quick, Trembley won't need the right-hander to reach a certain pitch count to be ready.
"I don't think it's pitches at all," he said. "Because I don't think he'd be a multiple-inning guy when he comes here. He's going to be a one-inning guy."
Uehara has been sidelined with a left hamstring strain, an injury sustained in a Grapefruit League contest this spring, and was placed on the disabled list March 26.
The expected roster move to add him is one of two moves facing the Orioles this week. The team's Saturday starter hasn't officially been announced -- although it is likely Brad Bergesen -- and the O's figure to lose a reliever in making that move.