The Cubs made a series of pitching moves ahead of this week’s tilt with the South Siders at Wrigley Field.

First and foremost, Marcus Stroman is no longer on track to come off the IL and start Wednesday’s game.

He is now experiencing right rib discomfort and will not start:

Marcus Stroman is experiencing some right rib discomfort, per Cubs. He won’t start tomorrow. #Cubs

— Andy Martínez (@amartinez_11) August 15, 2023

Stroman (hip inflammation) threw a 50-pitch bullpen on Friday and came out of it fine. He had another bullpen on Sunday and the original plan was for him to return on Wednesday when first eligible.

The Cubs now plan to start Javier Assad in Wednesday’s game.

“The doctors are checking him out today,” David Ross told Taylor McGregor prior to Tuesday night’s game. “We’re gonna get a lot of tests done and see where he’s at. It wasn’t anything that was super alarming but we’re not gonna know anything until he gets these tests back and he gets the MRIs and the scans and get more information from the doctor. We’ll know more then.

“I don’t have a whole lot other than we’re gonna start Javier Assad tomorrow and then we’ll slot Stro in as soon as we find out more information.”

In other pitching news, the Cubs called Michael Rucker back up to the big-league bullpen Tuesday afternoon and optioned Caleb Kilian to Triple-A Iowa.

Rucker, 29, has spent much of the season in Chicago. He has appeared in 34 games with a 5.03 ERA, 1.42 WHIP and 39 strikeouts in 39.1 innings. He was optioned to the minors on July 28 and posted a 1.50 ERA in 6 innings with Triple-A Iowa in that stint.

Kilian, a 26-year-old righty, has been with the big-league club for the last couple weeks as he was recalled from the minors on Aug. 6. He pitched a scoreless inning in relief on Aug. 7 and then surrendered 3 runs in an inning of work Sunday against the Blue Jays.