LAKE FOREST, Ill. – The Chicago Bears insist they were built to withstand injuries. Well, here comes the test.

Former Pro Bowl safety Mike Brown and starting defensive tackle Dusty Dvoracek are out with season-ending knee injuries, but the Bears’ expectations remain the same: A dominant defense.

They’ll just have to do it with Danieal Manning at free safety and veteran Darwin Walker at nose tackle, starting with Sunday’s home opener against Kansas City.

“I didn’t anticipate playing any less,” said Walker, acquired in a trade with Buffalo.

And his role won’t be diminishing anytime soon. Nor will Manning’s.

Not after Brown and Dvoracek were carted off the field together during the fourth quarter of last week’s 14-3 loss at San Diego. It was an ominous beginning to a season full of promise.

Brown’s year ended when Chargers fullback Lorenzo Neal wrapped his arm around his neck and threw him to the ground. Dvoracek got injured on a kickoff.

Besides losing Brown and Dvoracek, the offense went nowhere.

Chargers linebacker Matt Wilhelm told the North County Times that former Bears defensive coordinator Ron Rivera described quarterback Rex Grossman as a “mental midget.” And linebacker Shaun Phillips essentially called running back Cedric Benson soft in an interview with Sirius Satellite Radio on Tuesday, saying a little trash talk and hits rattle him.

Benson, who ran for 42 yards and fumbled once, laughed off Phillips’ comment. But Grossman rushed to Benson’s defense.

“Obviously, Cedric is one of the hardest runners in the league,” he said. “How many times have you seen him come into the hole and run somebody over? I mean he broke (Texans safety Glenn Earl’s) ankle in Houston.”