Antonio Gates is inactive

SAN DIEGO -- Antonio Gates will join Matt Cassel as a witness instead of a participant in the biggest AFC West game of the season on a perfect day in Southern California.

San Diego’s superstar tight end will not play Sunday because of a lingering foot injury. He missed two games and then returned for the past two games. Gates didn’t practice all week. Randy McMichael will start for Gates

San Diego (6-6) must win to stay alive in the AFC West race. Kansas City (8-4) could be on the doorstep of the AFC West title with a win. The Chiefs will be playing without Cassel, who had an appendectomy on Wednesday and did not travel with the team. Brodie Croyle will start at quarterback. Croyle is 0-9 as an NFL starter and hasn’t played since Week 13 of last season.

Meanwhile, Pro Bowl receiver Vincent Jackson will start for the Chargers. He missed last week’s game with a calf injury that he suffered on the second play of his season debut Nov. 28 at the Colts following a long holdout.