By Bruce Levine–

CHICAGO (CBS) — The Cubs have lost starting catcher Miguel Montero to back stiffness. as he’ll be placed on the 15-day disabled list. The move will officially occur either before or after Thursday afternoon’s game against the Brewers, with the timing depending on when replacement Tim Federowicz arrives in Chicago after being called up from Triple-A Iowa.

READ MORE: 15-Year-Old Among 2 Shot In West Englewood

Montero’s hitting .208 with one homer, six RBIs and a .649 OPS in 13 games this season. He was complaining of lower back pain for a while before sitting out Monday’s game. The Cubs medical staff then had Montero take an MRI on Tuesday, which Montero said he hasn’t received news on yet.

The move will be backdated to Monday, meaning he’ll be eligible to come off the DL on May 10. So Montero will be out for at least the next 12 games.

The 28-year-old Federowicz has appeared in 89 career big league games, most recently with the Dodgers in 2014. He signed a one-year minor league contract with the Cubs in January.

Federowicz and David Ross will split time behind the plate, manager Joe Maddon said.

“I don’t want to beat Ross up,” Ross said. “I would say two days in a row is what you would like to do with him. He will have (Jake) Arrieta and (Jon) Lester the next two days. You will probably see Federowicz the next day.”

READ MORE: Man's Body Pulled From Lake Michigan In Evanston, Hours After Crews Rescuing 3 Other People Find His Belongings On Beach

Montero has lower back pain before in his 11-year MLB career, he said. He missed about a month in July 2013 with a similar injury while with the Diamondbacks, and he had a minor league rehab assignment then as well.

“I did have this type of pain before, and I did not want it to get to that point again,” Montero said. “I will take it easy for a few more days and see how it goes.

“At this point, it’s been about four days and it’s still pretty tight. I might be able to back up and play, but what if I make it worse? It’s early in the year, so it’s better to take 15 days rather than a month or a month-and-a-half on the DL (later).”

The 32-year-old Montero wasn’t sure how the injury occurred.

“All the time this has happened to me in the past, it’s on the days I am not playing. Maybe you try to get ready a little too quick. I wish I had the right answer why it has happened. I guess it’s age, right? Something is there, and I know it’s been there. Mostly I have been able to control it by doing my core exercises. It’s a very uncomfortable feeling.”

Federowicz was hitting .303 with one homer and six RBIs in 11 games at Iowa. The Cubs chose to call up Federowicz instead of catching heir apparent Willson Contreras because they didn’t want to rush the latter’s development. Contreras is hitting .375 with an .866 OPS in 14 games at Triple-A Iowa later this season. Contreras could receive a late summer promotion after he gains more experience, Maddon said.

MORE NEWS: Chicago Weather: Last Weekend Of Summer May Be Among Nicest

Bruce Levine covers the Cubs and White Sox for 670 The Score and CBSChicago.com. Follow him on Twitter @MLBBruceLevine.