[Kansas City.com] Chiefs quarterback Brady Quinn is being evaluated for a possible concussion, and his status for Thursday night’s game at San Diego remains uncertain.

Coach Romeo Crennel on Monday said Quinn will start against the Chargers if he is cleared to play. Otherwise, Matt Cassel will be back under center for the Chiefs.

Quinn was hurt in the first quarter of Sunday’s 26-16 loss to the Oakland Raiders, though it is unclear when the injury occurred. He was sacked by Rolando McClain late in the first quarter, then took another shot while floating a pass that was picked by Matt Giordano.

Crennel said Quinn wasn’t at the practice facility Monday while he underwent tests, and Cassel would run the first-team offense during a walk-through practice.