According to major league baseball sources, Cubs right-handed pitcher Carlos Zambrano was placed on the 15-day DL with back pain Saturday.
Zambrano took himself out of his start Friday night against the Rockies after complaining about feeling tightness in his back during his bullpen session. He was also removed from his previous start against the Florida Marlins after three innings due to back pain.
According to sources, Zambrano left Denver on Saturday to return to Chicago for an extended battery of tests on his back at Northwestern Hospital.
In the meantime, the Cubs will most likely call up right-handed pitcher Jeff Stevens from Triple-A Iowa.