The Cubs have scratched Ted Lilly from his start on Saturday against the Cincinnati Reds because of shoulder soreness.
The team announced the move on Friday, when the left-hander was scheduled to undergo tests to determine the extent of the injury.
Chicago's only All-Star this season is 9-7 with a 3.59 ERA. He is coming off his worst start of the season, having allowed nine runs in four innings in Monday's 10-1 loss at Philadelphia. He had complained of soreness in his knee but this is the first time he has experienced shoulder pain.
The Cubs' starters are each moving up a day, with Kevin Hart going Saturday, Rich Harden starting Sunday and Carlos Zambrano pitching Monday's opener of a series against Houston.