Cubs' Trevor Williams: Joining rotation Tuesday

Williams is scheduled to start Tuesday's game against the Cardinals in St. Louis, Meghan Montemurro of the Chicago Tribune reports.

Jake Arrieta (hamstring) isn't available to begin the second half, so Williams will step into the Chicago rotation as the fifth starter after he previously worked as a bulk reliever July 6 in his first outing back from the injured list. Before missing time while recovering from appendicitis, Williams started in each of his first 10 appearances of the season and went 3-2 with a 5.36 ERA and 1.60 WHIP.