02:08 PM ET 11.20 | The Minnesota Vikings are preparing for one of their biggest games of the season on Sunday against the Chicago Bears, but uncertainty at quarterback could make those preparations even more difficult. Bears starting quarterback Jay Cutler missed Chicago's game against San Francisco on Monday due to a concussion, and his status for Sunday's game against Minnesota is still unknown. In addition to Cutler, the Vikings must also prepare to face backup Jason Campbell. Vikings head coach Leslie Frazier said the uncertainty poses a challenge for the Vikings. He said the two quarterbacks will not only pose different threats, but the play caller's mindset and how the offense runs will also vary. Vikings defensive end Jared Allen said preparing for the Bears' rushing attack is close to the same, but the passing offense between the two quarterbacks is different.