"It's a partial MCL tear and we are looking at three to five weeks," Jack Bechta said. "The MCL, all the guys that I've every had have come back. If there is any issue with uncomfortableness, they go in and get it cleaned up after the season."
Babineaux, who left Sunday's game in Chicago to have an ankle examined and re-taped, missed just three games during his first six NFL seasons, and he has started all but one of the Falcons' past 49 regular-season games.
The loss of Babineaux will be eased somewhat if defensive tackle Corey Peters, who has been out four weeks because of a knee injury, can return this week.