AFC West rivals meet up in this week's Thursday night game as the Kansas City Chiefs take on the San Diego Chargers at Qualcomm Stadium.  Matt Cassel will start at quarterback for the Chiefs with Brady Quinn out with a concussion.  Cassel returns under center after a concussion of his own in Week Five against Baltimore.  Kansas City has lost four straight to fall to 1-and-6.  The Chargers are looking to snap a three-game skid following Sunday's 7-6 setback at Cleveland.  The Bolts have lost four of their last five games overall to slip to 3-and-4, one game behind first-place Denver in the division.  San Diego beat Kansas City 37-20 at Arrowhead Stadium in Week Four.