The Cubs put left-handed reliever Donovan Osborne on the 15-day disabled list after Wednesday's game with St. Louis and recalled Scott Chiasson from Triple-A Iowa.
Osborne strained his right side muscle while making a pitch to the Cardinals' Jim Edmonds in the sixth inning. He was examined after the game by team orthopedist Dr. Michael Schafer.
Osborne, who once pitched for the Cardinals before injuries nearly forced him out of the game, had 1 2-3 innings of scoreless relief Wednesday. He has a 6.19 ERA in 11 appearances this season.
Chiasson has pitched 15 games in relief for Iowa with an 0-1 record, seven saves and a 6.46 ERA. He pitched for the Cubs last September, going 1-1 with a 2.70 ERA in six games.