All signs pointed to Alex Smith playing for the San Francisco 49ers tonight but the veteran quarterback has been ruled out because he could not get clearance from a neurologist to return from a concussion.

Smith will not play when the 49ers host the Chicago Bears on “Monday Night Football” at Candlestick Park, news first reported by ESPN’s Chris Mortensen. So, that means it will be Colin Kaepernick in his first career start against Jason Campbell, who is replacing Bears starter Jay Cutler, who is out with a concussion.

Smith practiced four days last week but could not pass the final test needed to be cleared to return to a game. This development certainly helps the Bears and their opportunistic defense. Smith had been doing a nice job of protecting the football and Chicago will look to pressure Kaepernick.

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Brad Biggs covers the Bears for the Chicago Tribune