Able to largely avoid the injury bug until now, the Chicago Bears may turn to second string quarterback Jason Campbell for Monday’s pivotal road matchup against the San Francisco 49ers.

Regular starter Jay Cutler suffered a concussion in Chicago’s brutal 13-6 loss to the Houston Texans and did not practice Thursday. Cutler banged helmets with Houston’s Tim Dobbins in the second quarter and finished the half, but had signs of a concussion during halftime and was pulled.

It is the third concussion for Cutler in his professional career, and according to the Chicago Tribune, might be his fourth total, counting his four years at Vanderbilt.

Since becoming a starter with the Denver Broncos in 2007, the 29-year-old has missed only seven games, with the bulk coming last year after he injured his knee and sat out six.

However, losing Cutler may not affect the Bears play that much. Chicago ranks 30th in the league in passing offense, and their rushing attack and overall defense have separated the team as one of the best in the NFC with a 7-2 record.

Signed in the offseason, Campbell led the Oakland Raiders to a 4-2 mark last season, but went down with a broken collarbone, which prompted Oakland to trade for Carson Palmer.

Formerly a first round choice by Washington in 2005, Campbell has a career passer rating of 82.6 and has just one season with a winning record, a 7-5 run in his first year in Oakland.

Chicago head coach Lovie Smith will probably not ask Campbell to do too much against San Francisco. The Bears will rely on running back Matt Forte, who is averaging 4.7 yards a carry, and a defense ranked second in points allowed, coupled with 26 sacks.

Chicago fans should also be encouraged by Campbell’s enthusiasm to take the field.

He said via Twitter Friday: “Never thought I'd say this on a Friday but, is it Monday yet??”

The 6-2-1 49ers are successful the same way was Chicago: rushing and total defense. Frank Gore and Kendall Hunter have shared carries this season, and San Francisco has given up the fewest points in the league thus far.

As insurance, Chicago also re-signed veteran Josh McCown Tuesday. The Bears cut him on Aug. 31, but have no other back-ups on their roster besides Campbell.