PITTSBURGH (AP) _ The San Diego Chargers found a way to get past Pittsburgh's new Steel Curtain _ they went over it _ and charged into their first Super Bowl.

Dominated nearly all game by the Steelers' blitz and unable to convert on third downs, the Chargers won by beating the blitz on a third-down, 43-yard touchdown pass from Stan Humphries to Tony Martin with 5:13 remaining. That dramatic play gave San Diego a 17-13 victory for the AFC championship, denying Pittsburgh a fifth trip to the Super Bowl.

The Chargers withstood a last-gasp Steelers' drive that carried to San Diego's 3-yard-line. Linebacker Dennis Gibson twice knocked down passes in the end zone _ the last one on fourth down _ preserving the Chargers' biggest NFL victory.

A franchise that won the AFL title in 1963 gets the chance for its first NFL crown on Jan. 29 at Miami. The Chargers will face either Dallas or San Francisco, both winners of four Super Bowls.

After Gibson's gems, several Chargers whipped out Terrible Towels to begin their celebrations. Meanwhile, the Three Rivers Stadium record crowd of 61,545 that came expecting to relive the 1970s, fell silent and began filing out.

It was the second sensational comeback for the Chargers. Last week, they trailed Miami 21-6 and rallied to win 22-21. This time, despite going 1-for-8 at one point on third downs and rarely giving Humphries enough protection, they struck for two big plays to turn it around.

The first came on a blown coverage during a blitz by Pittsburgh, leaving Alfred Pupunu wide open down the right sideline for a 43-yard TD.

The second, with two linebackers rushing, came against single coverage by Tim McKyer, who won two Super Bowls with the 49ers. Humphries threw the ball high and deep and Jefferson grabbed it beyond the desperate reach of McKyer.

After the game, McKyer, bent over and wobbly, needed help to walk off the field.

Meanwhile, Chargers linebacker Junior Seau, a star all day on defense, embraced Steelers quarterback Neil O'Donnell.

After the Steelers took a 13-3 lead on Gary Anderson's second field goal, a 23-yarder early in the third quarter, San Diego finally broke through on Pupunu's score.

Amazingly, despite being thoroughly outplayed, San Diego still was in the game. The Chargers had completed one pass to a wide receiver, yet were in striking distance because of Steelers mistakes, particularly holding penalties deep in San Diego territory.

Then Humphries, who was severely outplayed by his O'Donnell, took them 80 yards to victory _ and the Super Bowl, a place virtually nobody gave them a chance for when the season began. Or even before this game.

Even though the Chargers beat Pittsburgh 37-34 in the season finale, they were 8-point underdogs. The Steelers finished with the No. 1 rushing game in the NFL and the No. 3 pass defense, even though they sat out four key players at San Diego.

But the pass defense fell apart at the worst times and the runners were stymied by All-Pro Seau and a powerful front line _ Barry Foster gained only 47 yards as Pittsburgh rushed for 66.

It was left to O'Donnell to get them to Joe Robbie Stadium on Jan. 29. O'Donnell set AFC championship game records by going 32-for-54 for 349 yards and a touchdown.

O'Donnell, the man many believed could keep the Steelers out of the Super Bowl nearly got them there instead.

Steelers receiver Ernie Mills also had a career day with eight catches for 106 yards. Mills converted five third downs, including two catches of 19 yards and two of 18, as Pittsburgh dominated most of the game.

Typically, the Steelers had the ball for 37:13. Untypically, they didn't take full advantage of the possession differential.

The Steelers nearly gave the ball away after stopping San Diego's second drive. Rod Woodson muffed Bryan Wagner's punt near midfield, but the ball was touched out of bounds by several players, giving the Steelers the ball at their 49.

Two plays later, the team that led the NFL with only 17 turnovers gave it away. Foster was hit by Chris Mims and lost the ball, which Darren Covington pounced on at the Chargers' 41.

But Pittsburgh's defense barely budged. Means ran for 18 yards on three plays, and a sack by rookie Brentson Buckner forced a punt.

Once again, the Steelers' undaunted attack kept the clock moving. Once again, a mistake killed the drive, which went from their 12 to the Chargers' 27. Duval Love was caught holding, and Pittsburgh punted.

Yet another error cost Pittsburgh 46 yards. After Means ran for 17 and the Chargers completed their first pass _ with 6:08 left in the half _ for 15 more yards, Humphries went deep for Shawn Jefferson. He practically was tackled at the 2 by Deon Figures. The interference call set up San Diego for the tying touchdown, but it never came.

Just as in the the opening half of their 22-21 victory over Miami last weekend, the Chargers struggled when close to the end zone. Means was slammed back three times, twice by inside linebacker Levon Kirkland, and San Diego settled for a 20-yard field goal by John Carney, the league's leading scorer.

Back came O'Donnell with completions of 19 yards to Ernie Mills and 14 to Andre Hastings on third downs. An 18-yarder to Mills, again on third down, got the ball to the 12 before _ what else? _ a holding penalty on Leon Searcy stymied the march.

Anderson's 39-yard field goal made it 10-3 at the half, not a very big margin considering Pittsburgh had the ball for more than 22 minutes.

The Steelers outgained the Chargers 229 yards to 46 in the first half, and ran as many plays as the Chargers had yards.