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.
Tillman suffered a torn right triceps muscle in the second half Sunday, and has been placed on injured reserve/designated to return. He can return to practice in six weeks and is eligible to play again in eight weeks. The Bears (5-4) have seven games remaining in the regular season.
"The fact that I'm no longer a part of that to help this team further succeed, that's the part that hurts," said Tillman, a two-time Pro Bowl player. "My role right now is to be the biggest cheerleader and supporter on the sideline."
The Bears defense already was without three starters in linebacker Lance Briggs (shoulder fracture), defensive tackle Henry Melton (ACL tear) and linebacker D.J. Williams (torn pectoral muscle).
"It just so happened, the injury bug, it has a hold of our team for some reason," Tillman said.
Trestman said Cutler's injury occurred almost three minutes into the second quarter when a defender rolled up his ankle. Cutler continued to play, but left before the game's final drive.
Trestman said he never thought Cutler reached the point where his play was hindering the team until his final pass, one made on the run that went into the ground in front of wide receiver Alshon Jeffery.
"It's very tough to pull your starting quarterback out when he's throwing the ball with velocity, when he's hitting his receivers and he's able to move in the pocket and complete a throwing motion," Trestman said. "All those three indications confirmed with me that I should keep him in there. I know we sacrificed his ability to move around and run (by keeping him in), but that was the case after two minutes and 53 seconds of the second quarter. So I feel good about what we decided to do with him."
After the game, Cutler called the decision to pull him an on-going evaluation throughout the game.
"I knew Josh was ready to go and I just didn't want to get to the point where I was hurting us more than I was helping us," Cutler said.
Cutler had missed the previous game against Green Bay with a torn groin muscle. He played Sunday following only three weeks away after the team originally said he'd miss four weeks or longer.
Trestman again repeated Sunday's statement that Cutler's groin injury has nothing to do with the ankle injury.
"I asked (doctors) if the groin was an issue at all," Trestman said. "They told me even today that if he hadn't rolled up the ankle he would have been able to play today."
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.
"He's a veteran," Tillman said of Bowman. "He's been in this defense a while. He's been a starter on this defense before Tim got here. So I think Zack Bowman is a good fit. He's the next man up and I have nothing but confidence and faith in Zack."
Tillman, like Cutler, is in the final year of his contract and it's often been suggested the 33-year-old corner should be converted to free safety as he ages.
"I think my athleticism is still there to play corner in this league, whether it be for the Bears or somebody else," Tillman said. "But I still think I have some corner left in me."
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