Kansas City quarterback Matt Cassel missed Wednesday's practice and his availability for this weekend's AFC West showdown at San Diego wasn't immediately known.
Coach Todd Haley said Cassel had an undisclosed illness and wouldn't discuss his quarterback's availability for Sunday's game. The Chiefs have a two-game lead over the Chargers in the division with four to play.
Haley also said it's only a coincidence that third-string quarterback Tyler Palko was promoted off the practice squad Wednesday. The backup is Brodie Croyle, who has not played this season.
In his second season as Kansas City's starter, Cassel has blossomed into one of the league's most consistent quarterbacks. His four interceptions are the lowest total among NFL quarterbacks, and he's a prime reason the Chiefs are 8-4.