Chicago Cubs pitcher Marcus Stroman has experienced a major setback in his aim to return to action.

The 32-year-old right-hander initially joined the injured list on July 31 following his start that day. He was first scheduled to return to action on August 18 against the Chicago White Sox but, following a bullpen session in Toronto last Sunday, he experienced discomfort in his ribs.

On Wednesday, Stroman's injury was officially announced by the team as a right rib cage cartilage fracture and, apparently, this injury is not seen very often on the diamond.

“It’s rare, very rare,” Stroman said, according to The Athletic. “They don’t see it much in baseball. With what they recommend, it’s kind of a gray area I feel. I trust a lot of doctors that have seen the MRIs, so I’m going to put trust in them and go from there.”

The injury news couldn't have come at a worse time for the Cubs, who are currently trying to assemble a playoff push and had generated some real momentum throughout the month of July, but have slipped up a bit recently, dropping three of their last four.

It's now unclear when or even if Marcus Stroman will return at all this season. The fact that the injury is so rare in baseball makes it difficult to navigate, as there is not much precedent for return timetables.

Cubs fans will certainly hope that Stroman is able to work through this setback sooner rather than later and return to the mound before it's too late.