Freeney, an 11-year veteran and a seven-time Pro Bowl selection, injured his ankle in the first quarter and did not return. He did not record any tackles in the Colts' 41-21 loss.
"We'll go back, and I'm sure they'll do a MRI on Dwight and see what the severity of that is," Colts coach Chuck Pagano said. "He'll be day to day."
Pagano did believe Freeney's absence affected the defense. In the Bears' first two possessions, the Colts forced them to punt and returned an interception for a touchdown. With Freeney out, the Bears then scored 17 of their 41 points in the second quarter.
"Nobody wants to see a guy of Dwight's caliber go that early in the ballgame," Pagano said. "It's kind of deflating."