Philip Rivers, who missed on 19 of his first 27 passes, found Vincent Jackson alone in the end zone for a 37-yard touchdown pass with 29 seconds left to send the Chargers to their ninth straight win, 20-17, over Seattle on Sunday.
But the Seahawks' sting was somewhat soothed by Arizona's upset at San Francisco minutes earlier. That meant Seattle (8-7) clinched its third consecutive NFC West title despite its third straight loss.
San Diego (13-2), the AFC West champion, knew it could not clinch top seeding in the conference because Baltimore (12-3) won earlier Sunday at Pittsburgh. The Chargers will need to beat the Cardinals at home next week to ensure home-field advantage throughout the postseason.
Shaun Alexander ran for 140 yards and both Seattle touchdowns to rally the Seahawks from a 10-0 deficit in the second half. His spinning, nine-yard score put the Seahawks up, 14-13, with 13 minutes left. A field goal by Josh Brown with five minutes to go increased that lead.
But then Rivers, who struggled again after an eight-for-23, two-interception game last week, got going. He completed two throws for 24 yards before Jackson caught safety Michael Boulware cheating up on a deep pass route. Jackson easily slipped behind Boulware for his second touchdown catch of the game.
Seahawks Coach Mike Holmgren chose to look past the stunning finish and the two bad division losses that preceded it.
"This doesn't have to be a morgue," Holmgren said. "To be honest with you, I am more on the upbeat side than the downbeat side. That's a good football team, the Chargers.... There were a lot of good things that happened today. I'll take it."
San Diego set a franchise record for victories in a season despite a relatively modest day from LaDainian Tomlinson, the favorite to be voted the league's most valuable player. Tomlinson had 123 yards in 22 carries, his ninth consecutive 100-yard game. Rivers missed on his first nine passes and finished 10 for 30 overall for 181 yards.
Seattle quarterback Matt Hasselbeck was 17 for 37 for 189 yards. He threw two passes that were intercepted in the first half.