Coach Matt Eberflus said Friday that Siemian will undergo season-ending surgery on his oblique, Jason Lieser of the Chicago Sun-Times reports.
Siemian was slated to fill in for an absent Justin Fields (shoulder) this past Sunday at the Jets, but he injured his oblique in warmups and suddenly was a game-time decision. He ended up playing through the pain and logged all 56 offense snaps in the loss while completing 14 of 25 passes for 179 yards, one touchdown and one interception. In the wake of the performance, Siemian was unable to practice during Week 13 prep and now will be sidelined for the rest of the campaign. Fields is in line to return Sunday against the Packers, and Eberflus noted practice-squad member Nathan Peterman will be the backup quarterback, even with the Bears signing Tim Boyle of the Lions' practice squad Wednesday.