context:  Hoping to rebound from their loss to the Chargers, the Raiders flew to Arrowhead Stadium for a Week 2 AFC West duel with the Kansas City Chiefs.  Oakland would trail in the first quarter as Chiefs kicker Ryan Succop got a 23-yard field goal.  The Raiders would tie the game in the second quarter as kicker Sebastian Janikowski got a 48-yard field goal.  In the third quarter, Oakland took the lead as Janikowski nailed a 54-yard field goal.  In the fourth quarter, Kansas City took the lead as quarterback Matt Cassel completed a 29-yard touchdown pass to wide receiver Dwayne Bowe.  Afterwards, Oakland claimed victory as running back Darren McFadden got the game-winning 5-yard touchdown run.
question: Who did the Radiers lose to prior to playing this game with the Chiefs?
answer: Chargers