CHICAGO - Already reeling from a lopsided loss to the Dallas Cowboys, the Chicago Bears could be without Pro Bowl defensive tackle Tommie Harris for an extended period of time.

The Chicago Tribune reported Tuesday that Harris could be sidelined for up to a month with a left knee injury suffered in the fourth quarter of Sunday’s 34-10 defeat to the Dallas Cowboys.

Harris’ agent, Bill Horn, told the Tribune that Harris underwent an MRI exam on Monday that revealed a medial collateral sprain in his left knee.

Last season, Harris missed the final four regular-season games and the playoffs with a torn hamstring tendon.

The defending NFC champions dropped to 1-2 following the loss to the Cowboys and have been hit hard by injuries to their defense.

Pro Bowl linebacker Lance Briggs (groin) and Pro Bowl cornerback Nathan Vasher (hip) also were injured against the Cowboys.

The Bears had already lost defensive starters Mike Brown and Dusty Dvoracek to season-ending knee injuries. Dvoracek is scheduled to have surgery Tuesday.

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