Bears' Tillman out with back injury

CHICAGO, July 28 (UPI) -- Starting Chicago Bears cornerback Charles Tillman will be out indefinitely with a back injury, the Chicago Tribune reported Tuesday.

Citing unnamed team sources, the Tribune said Tillman, the team's most dependable defensive back, will miss the opening of training camp but could return in time for the Bears' final preseason game on Sept. 3. Tillman recently underwent an arthroscopic surgical procedure to clean up a disc in his back, the newspaper said.

Tillman's uncertain status will put more pressure on Chicago's defensive secondary to improve their performance, analysts said. His absence could affect Corey Graham, whom the Bears moved from cornerback to free safety this spring, and Nathan Vasher, who will now be counted on to return to his All-Pro form of three years ago, the Tribune said.

The situation will also provide an opportunity for second-year cornerback Zack Bowman, who reportedly provided one of the pleasant surprises of the Bears' off-season workouts.