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SAN DIEGO (Reuters) - The New York Jets pulled off a surprise 17-14 win over the San Diego Chargers Sunday to earn an AFC Championship showdown with the Indianapolis Colts.

The Jets trailed 7-3 going into the fourth quarter but snatched the lead with a touchdown when rookie quarterback Mark Sanchez threw a short pass on the run to Dustin Keller.

Another Jets rookie, running back Shonn Greene, then gave the Jets a 17-7 lead with an explosive 53-yard touchdown run.

San Diego's Nate Kaeding missed his third field goal of the day as the Chargers tried to respond. It was a nightmare game for kicker Kaeding, who had converted his previous 20 kicks going into the game.

Quarterback Philip Rivers ran through the middle from a yard out to bring the Chargers within three points, but it was too late for a team that had gone 13-3 in the regular season.

The Jets scrambled into the postseason with a 9-7 record and are now one more upset win away from a place in the Super Bowl.

But first year coach Rex Ryan said he did not consider the win, which takes his team to their first AFC Championship game since 1998, to be a shock.

"Not really -- we have believed the whole time, the whole year," said Ryan.

"It (the win) probably wasn't the popular choice but its been old fashioned 'ground-and-pound' football and here we are."

The first half was a grueling, unattractive battle with San Diego getting in front in the second quarter on Rivers' 13-yard pass to full-back Kris Wilson in the end-zone.

A 46-yard field goal from Jay Feely put three points on the board for the Jets in the third before the two quarterbacks exchanged interceptions.

WEATHER THE STORM

The fourth quarter belonged to the Jets, with Sanchez delivering the key plays.

"In games like this you have to weather the storm," said the quarterback, who was drafted from the University of Southern California.

The Jets now face a Colts team who effectively eased New York's path into the playoffs by resting key players and losing to them in the penultimate round of the regular season.

Chargers coach Norv Turner was at a loss to explain the defeat.

"You'd like to be playing your best games in January, in games like this. Certainly for whatever reason, we did not do that today," he added. "We didn't play our best game and it's disappointing."

The Chargers had scored at least 20 points in their past 22 games, a run that ended with a bump.

"There's no one thing you can point at," defensive end Luis Castillo said. "There's no one thing where you can point the blame. We made a lot of mental mistakes in terms of penalties and personal fouls."

(Reporting by Simon Evans in Miami; Editing by Peter Rutherford)