The Chicago Cubs were planning on Marcus Stroman returning from the injured list to pitch Wednesday.

It turns out he will be sidelined much longer.

Stroman has been diagnosed with a right rib cartilage fracture and is out indefinitely.

Already on the IL due to right hip inflammation, the 32-year-old experienced rib discomfort recently during his rehab and the Cubs announced Tuesday he would not be activated to pitch against the Chicago White Sox the following night.

At this point, the Cubs are going to wait until he's pain-free until he resumes throwing.

While the team is not giving a timeline for his return, recovery for such an injury could be anywhere from two weeks to up to six weeks.

With only 6 1/2 weeks left in the season, it's possible he's done for the year.

It's a tough blow for a Cubs team that entered Wednesday 3 1/2 games behind the first-place Milwaukee Brewers in the NL Central and one game back of the Miami Marlins for the final wild-card spot in the NL.

Stroman, who was Chicago's opening day starter, was sensational early in the season, going 9-4 with a 2.28 ERA in 16 starts through June 20 and earned his second All-Star team selection. At that time, his ERA was the lowest in the NL among the 37 pitchers with at least 70 innings thrown.

The last two months have not gone nearly as well for him, as he's gone 1-4 with a 9.00 ERA in his last seven outings and landed on the IL on August 2.

Despite his recent struggles, the Cubs were hoping a stint on the IL would help Stroman regain his early season form, but now the team is facing the real possibility he won't be able to pitch the rest of the year.