St. Louis third baseman Scott Rolen will likely sit out the three-game weekend series in Pittsburgh because of back spasms that forced him out of Wednesday night's game in Cincinnati. Rolen initially had discomfort during batting practice and was lifted after going 0-for-2. He sat out of Thursday afternoon's game against the Reds and felt better Friday, but manager Tony La Russa doesn't expect him to start again until Tuesday. "I think he needs to feel like he's 100 percent before we consider it," La Russa said. "We'll see how much progress he makes ... but I don't see us changing until Tuesday."