The Cubs’ starting pitching plans this week changed when right-hander Marcus Stroman felt discomfort on the right side of his ribs. 

He was originally scheduled to be activated off the 15-day injured list to start Wednesday. He’ll be evaluated by the Cubs medical staff, but it was already clear Tuesday afternoon that he would not be pitching Wednesday. Instead, Javier Assad will “more than likely” start  against the White Sox on Wednesday, manager David Ross said.

“We’ve got to wait and see,” Ross said when asked his level of concern Tuesday before the two-game crosstown series opener at Wrigley Field.

Stroman landed on the IL two weeks ago with inflammation in his right hip. He received a cortisone shot and ramped up to a game-like bullpen session on Friday. Both his health and mechanics were trending in the right direction. But after a light bullpen session on Sunday, Stroman’s rib began bothering him later in the day, Ross said. 

“The one positive to all this is Javier Assad’s thrown the ball really well,” Ross said.

As long as Stroman’s new ailment doesn’t force an extended delay, the Cubs have the off days and personnel to manage his absence. The Cubs are coming off a Monday off day and have another day off Thursday. 

Assad in his last start held the Blue Jays to one run through seven innings. Wednesday will mark his third start since Stroman landed on the IL.