Chicago Cubs right-hander Marcus Stroman is dealing with right rib discomfort, delaying his return from the injured list.

Stroman was placed on the 15-day IL on Aug. 2 with right hip inflammation. The All-Star was slated to start Wednesday against the White Sox, but manager David Ross said Stroman had some discomfort in the rib area after throwing a bullpen session Sunday in Toronto.

"Concern is just ... we've got to wait and see," Ross said Tuesday.