On the same day the Cardinals will add one potential center fielder to the active roster, their starter at that position will be set to begin a rehab assignment. Jon Jay, who has been on the disabled list the past month with a shoulder sprain, is scheduled to join Class AAA Memphis in Omaha on Tuesday to begin his rehab assignment. Jay took live batting practice Sunday for the first time, and if he gets comfortably through another round today at Busch Stadium he'll be green-lighted for Memphis' lineup. The same day Jay starts his way back to the majors, Skip Schumaker, who missed two weeks with a strained hamstring, will join the big-league club in Detroit, ready to play. "Medically things are looking up," general manager John Mozeliak said Sunday afternoon. "We're not over the hump yet, but looking up."