The bullpen session was the first for Uehara since he was forced to leave a May 23 game against Washington with a strained left hamstring. If all goes as planned, Baltimore's first Japanese-born player will throw off a mound once more before facing Seattle at Camden Yards following a road trip that begins Monday.
Uehara has long had problems with the hamstring, and he's still getting used to pitching with four days rest. He served as a middle reliever in Japan before signing with the Orioles as a free agent in January, and has already logged 50 2/3 innings compared to 89 all last year with the Yomiuri Giants.
Manager Dave Trembley said the stint on the DL will probably be "advantageous" to Uehara in the long run.
"We're trying to do everything we can to make sure he can pitch in August and September," Trembley said. "If you look at the amount of innings he threw last year and what he's thrown this year, it's almost equal already. We have to be very smart about it."
Asked how the rotation might change upon Uehara's return, Trembley chose to take a wait-and-see approach.
"We've got time," the manager said. "Let's watch, evaluate, then when Koji is ready we'll make a decision."