The Bears (3-1) head into their first season under coach John Fox with some big holes and a long list of injuries, particularly at receiver.
Fales completed 14 of 18 passes for 131 yards with Jay Cutler getting the night off and backup Jimmy Clausen recovering from a concussion.
The defense had seven sacks and three takeaways, helping Chicago prevail on a night when both teams held out almost all their top players.