CHICAGO — The Cubs will be without their rookie phenom to start the 2025 MLB playoffs.

The team announced Saturday afternoon that it had placed rookie right-hander Cade Horton on the 15-day IL with a right rib fracture and recalled left-hander Jordan Wicks to take his roster spot.

“He was sick the weekend we were in Cincinnati, was coughing, ribs were kind of sore, and he went out and pitched — I guess that was on Tuesday, and he felt it, and so we were concerned,” Cubs president of baseball operations Jed Hoyer said on the Marquee Sports Network broadcast of Saturday’s game against the St. Louis Cardinals. “We took him out of the game and obviously found out he has a fractured rib.”

Despite the injury, Horton was scheduled to throw a bullpen session Sunday afternoon at Wrigley Field in hopes of being a potential Game 1 starter in next week’s NL Wild Card Series against the San Diego Padres. He even threw on the field before Saturday’s game against the St. Louis Cardinals.

“He threw yesterday, he threw today,” Hoyer said. “And then when he threw today, it was just very clear that there was just simply no way for him to pitch without changing his mechanics and even being effective.”

Horton exited his start Tuesday night against the New York Mets after three innings because he felt some discomfort in his back. He underwent imaging Wednesday and received a second opinion that allowed both he and the Cubs to feel comfortable with moving forward with ramping up. Clearly, the symptoms persisted enough that Horton can’t pitch for the next two weeks.

The roster move is backdated to Sept. 25, meaning Horton can’t return until at least Oct. 10, which is the day before Game 5 of the NL Division Series, but he won’t be able to be added to that roster, meaning the earliest he could return is for the NLCS.

“He wanted to give it a shot, but there was just no way,” Hoyer said. “He realized it, we realized it, and we’ll see. If we keep advancing, I’m not going to limit that. But certainly for the near-term, he needs to not throw and let this thing heal.”

It’s difficult news for the Cubs to swallow, as Horton had a 1.03 ERA and 0.78 WHIP in 61.1 innings across 12 starts after the All-Star break. He finishes his first MLB regular season with an 11-4 record, 2.67 ERA and 97 strikeouts in 118 innings, and he should be an NL Rookie of the Year front-runner.

With Horton out, the Cubs likely will turn to either Matthew Boyd or Shota Imanaga to open their first playoff appearance since 2020. The left-handers have been solid starters this season, but both have hit roadblocks late this season.

Imanaga has a 6.51 ERA in five September starts and given up 10 home runs in that time. He had his worst start of the year to end the season, allowing eight runs on nine hits in 5.2 innings against the Mets on Thursday.

Boyd, an All-Star this season, had a strong outing Wednesday against the Mets, allowing just two runs in 5.1 innings, but he had a 5.77 ERA in his eight starts before that outing.

The Padres have struggled against left-handed pitching this season, posting a .684 OPS against southpaws, just the 19th-best mark in baseball.

Boyd faced the Padres twice in April — he threw six scoreless innings in a 7-1 win on April 5, then allowed two runs on six hits in 5.1 innings in a 4-2 loss on April 16 in San Diego. Imanaga beat the Padres on April 4, throwing 7.1 innings of one-run ball at The Friendly Confines, and allowing only one run over five innings on April 15 in San Diego.

If those two start the first two games of the series, that likely would leave either Colin Rea or Jameson Taillon as options in a potential Game 3, although that would be an all-hands-on-deck type of game.