Cutler, who left Sunday's 21-19 loss to the Detroit Lions, has a high left ankle sprain and will miss Sunday's game against the Baltimore Ravens. He is listed as week to week by the team and Josh McCown will start.
''This is a week to week (injury), and it certainly won't be this week,'' coach Marc Trestman said Monday about Cutler's return.
McCown, who started and played throughout the 27-20 win at Green Bay on Nov. 4, played the final series against the Lions and led the Bears on a touchdown drive. A tying two-point conversion run by Matt Forte failed after McCown threw a TD pass to Brandon Marshall.
With McCown taking Cutler's place against the Ravens, Zack Bowman will replace Tillman. He has started 17 NFL games, including 12 in 2009 prior to the signing of free agent cornerback Tim Jennings.