KANSAS CITY, Mo. -- The San Diego Chargers got lucky. Even better, they've got Philip Rivers.

After their onside kick bounced off Chiefs wideout Dwayne Bowe's chest and Kassim Osgood recovered for San Diego, Rivers needed just four plays Sunday to complete one of the most stirring comebacks of the season.

With 1:13 left, Rivers hit Malcom Floyd with a 4-yard TD pass. Then his 10-yarder to Vincent Jackson with 36 seconds to go lifted the Chargers to a 22-21 victory over the stunned Chiefs, who led 21-3 in the third quarter.

"We never stopped believing," said Chargers tackle Marcus McNeill. "I think (the Chiefs) thought they had the game won when the clock was low in the fourth quarter. But we knew if we got another chance that we were going to go down there and score."

After their try for a two-point conversion failed, the Chargers (6-8) still needed help from the football gods. Aided by a delay-of-game penalty, the Chiefs (2-12) tried a 50-yard field goal on the final play. Connor Barth, who had been nine-for-nine before missing a 34-yarder in the first half, was wide left.

"I'm kind of speechless. Don't know what to say," Barth said. "There's no excuse."

Rivers, who came in with an NFL-best 102.0 passer rating, was 34-for-48 for 346 yards and two touchdowns when his team needed them the most.

But he could hardly bare to watch Barth's attempt at the winner.

"I had a pretty good view and a pretty sick stomach," he said. "I was just thinking, 'There is no way this can happen again.' He certainly had plenty of leg, but just missed it left."

A loss would have officially eliminated San Diego's slender playoff hopes. But Rivers said the Chargers, preseason Super Bowl favorites, would not let even a Denver victory over Carolina later Sunday dampen the thrill of beating KC.

"There have been so many doubts and we've fallen so short of the expectations," he said. "The way we've bounced back these past two weeks in our division and won says a lot about our guys. It is big for our locker room and team, no matter what plays out the rest of the day."

The Chiefs will have to win their final two games to avoid setting a franchise record for fewest wins in a 16-game season.

"I'm still in utter shock right now," said linebacker Rocky Boiman. "How we can come so close and still somehow let it slip away, it doesn't seem possible."

Losing a 21-3 lead is not even the worst thing that's befallen the Chiefs in this miserable season. Against Tampa Bay, they squandered a 24-3 advantage, a team record.

Bowe, who caught a 1-yard TD pass from Tyler Thigpen, appeared to have the onside kick.

"I think sometimes he takes his eye off the ball," said Chiefs coach Herm Edwards. "Those are plays you have to make along the way."

After the onside kick, Rivers' first play produced a 39-yard pass to Vincent Jackson to the 19.

Thigpen threw for one touchdown and ran for another for the Chiefs and was 19-for-28 for 171 yards.

The Chargers had three turnovers and, perhaps more embarrassing, gave up three sacks to the NFL's worst pass rush. Tamba Hali had two sacks and caused two fumbles for a Chiefs defense that hadn't gotten a sack since playing San Diego four games ago.

The three sacks pushed KC's season total to a league-low nine, and the Chiefs need five in their last two games to avoid tying the NFL record for fewest in a season.

Running back Larry Johnson capped a 96-yard drive with a 4-yard TD pass to Tony Gonzalez on KC's first possession.

Patrick Surtain's 50-yard return of an interception set up Thigpen's 3-yard TD in the third period.

Notes

• Larry Johnson is the fifth player to throw a touchdown pass for Kansas City this year and the seventh to throw Tony Gonzalez a TD pass in his career. Johnson is the sixth in team history to throw, run and receive for a TD.
• Temperatures hovering in the low 60s when early-arriving fans first showed up, had plunged into the 20s by the end of the game.
• The Chargers beat the Chiefs twice this year by a total of two points.
• The Chargers have given up five of KC's nine sacks.