PHILADELPHIA -- Rookie Jonathan Pettibone went on the disabled list on Friday with a strained right shoulder, which he said first bothered him during the Phillies' three-game series in St. Louis last week.
Pettibone made two starts after feeling the initial discomfort. He was scheduled to pitch against the Braves on Saturday, but after he threw a bullpen session on Wednesday that he said "didn't go well," the team decided to put him on the DL.
Pettibone doesn't think the injury is serious, and he doesn't plan to undergo an MRI.
John Lannan will take the mound on Saturday on three days' rest. Cliff Lee, who has not pitched since July 21 because of a stiff neck, will start Sunday night's contest
Pettibone was called up in mid-April, and in 18 outings (100 1/3 innings) has gone 5-4 with a 4.04 ERA.
"This is the most he's pitched," manager Charlie Manuel said. "From what I hear, and what I see on the reports, it's nothing too serious yet. We just want to give him a little time, that's all."
Stephen Pianovich is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.