Montgomery was placed on the 10-day disabled list with a left elbow strain Wednesday.
The southpaw was lifted from Tuesday's contest after just one inning of work due to elbow soreness, but that has since been upgraded to a full-blown elbow strain. It's unclear how long he'll be out, but elbow injuries are never a good sign for pitchers. David Hale will replace Montgomery on the active roster, though Domingo German seems like the top candidate to slide into the rotation to replace him.