Bill Cowher and the Steelers will need a better performance next week if they hope to advance to the Super Bowl. Andy Lyons/Getty Images

PITTSBURGH -- Their gaudy 14-game winning streak was as good as over. Another hard-earned No. 1 seed and AFC's home field advantage throughout the playoffs appeared squandered. The distinction of having the league's top-ranked defense, a historic rookie sensation at quarterback, and an almost season-long ride on an ever-building wave of momentum looked to be just so much empty window-dressing.

And then, miraculously, these Pittsburgh Steelers received the gift of new life. Two gifts, actually, in the form of a pair of missed field goals by New York Jets kicker Doug Brien -- both in the final two minutes of regulation.

Boil it all down and about the best you could say for the Steelers on Saturday night at Heinz Field was that they won. They survived. They move on. They're in the NFL's final four.

But the stark truth that was revealed in Pittsburgh's 20-17 overtime victory against the upstart Jets is that these Steelers are beatable. They are not a machine after all. They are not infallible, and hardly invincible. In fact, winning streak or no winning streak, they are suddenly vulnerable. And they are darn fortunate -- thank-your-lucky-stars fortunate -- that they avoided tacking on another ignominious chapter to their desultory postseason track record in the 13-year Bill Cowher coaching era.

Whatever the Steelers bring to next Saturday night's AFC Championship Game at Heinz Field, it better be a far superior display of football than the one they got away with against New York. Because no matter who wins Sunday in Foxboro, Mass. -- the hometown Patriots or the powerful Colts -- Pittsburgh won't be able to handle either one of them next week with the same effort that eliminated the plucky, but ultimately unlucky, Jets.

And nobody knows that better than the Steelers themselves. After all, does anybody think Adam Vinatieri would have missed both of those field-goal attempts? How about Mike Vanderjagt?

"We won the game, but we certainly didn't play our best game,'' Cowher said, in perhaps the day's most whopping understatement. "We're going to have to play better if we want to move on. There's no question we were fortunate. But we won the game and that's what is most important.''

Added a duly chastened Steelers linebacker Joey Porter: "This is good for anybody who thought it was going to be easy in the playoffs. It was that little kick in the behind that we might have needed. We were tested today, tested as a team. To see if we were going to fold when we faced some adversity.''

By almost every measure, the Steelers this season seemed primed for a memorable Super Bowl run, with all the pieces in place for a championship: great defense, stout running game, mistake-free quarterbacking. But those pieces were very nearly shattered into a million meaningless fragments against the wild-card Jets, the team that came within the width of a goal post of forcing us to embrace them as a member of the AFC elite.

The only thing standing between the Steelers and just another playoff home field embarrassment was Brien, whose glaring failures from 47 and 43 yards gave Pittsburgh the reprieve it needed to set up kicker Jeff Reed's game-winning 33-yard field goal with 3:56 left in overtime. It was the first time all season that Brien has missed two field goals in a game, and it came just seven days after he won New York's first-round playoff with a 28-yard field goal late in overtime.

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"Last week was great, this week sucks,'' said Brien, succinctly. "I just feel bad for the team. I mean, I'll be fine. I just feel bad for the guys who played so well.''

That would be the Jets' guys, not the Steelers' guys. Afterward, nobody dared accuse Pittsburgh of playing well. The Steelers' magical season very nearly disintegrated beneath an avalanche of mistakes and missed opportunities, as some of their old reliables suddenly proved not quite ready for their playoff close-ups.

For starters, there was Steelers rookie quarterback Ben Roethlisberger, who picked the worst possible time to finally look like a rookie: with two interceptions, a 57.8 quarterback rating, and just one touchdown and 181 yards on 17-of-30 passing. One of his picks was returned 86 yards for a go-ahead touchdown by Jets strong safety Reggie Tongue, putting New York up 17-10 late in the third quarter.

Roethlisberger rarely resembled the calm, cool and collected precision passer that he has been all season. He was inaccurate on the run for the first time this year, appeared to have problems getting a good grip on the ball while wearing gloves in the cold weather, and put his team in a hole it had no right to recover from.

"It wasn't me out there today,'' said Roethlisberger, who has won all 14 of his starts since taking over for the injured Tommy Maddox in Week 3. "It was tough going, and I did everything I could to lose the game. I didn't [feel nervous]. But maybe I should have. Maybe next week I need to be a little more stressed, a little more nervous.''

And Roethlisberger wasn't alone. Steelers running back Jerome Bettis gained a game-high 101 yards rushing on 27 carries, but he also lost his first fumble of the year, which ended a promising early fourth-quarter Pittsburgh drive at the Jets' 23. The Steelers trailed 17-10 at the time, largely on the strength of New York's two return touchdowns -- Tongue's, and the 75-yard Santana Moss punt return that tied the game at 10-10 with 3:00 remaining in the first half.

"Defensively we played a pretty good game,'' Cowher said. "We gave up only three points. We didn't give up a touchdown. But we've got to play better than we did.''

In the Pittsburgh locker room, relief was mixed with respect for the Jets, who played their NFL record third consecutive overtime game. The Steelers struggled to beat New York 17-6 at Heinz Field five weeks ago, in a game that was tied at 3-3 early in the fourth quarter. But Pittsburgh was never in jeopardy of losing that game. This one came down to a pair of Jets field-goal attempts that most Steelers could barely stand to watch.

"We probably should have lost that game, really,'' Pittsburgh center Jeff Hartings said. "We made a lot of mistakes. You don't expect them to miss two field goals and get that many chances, that's for sure.''

Said Steelers linebacker James Farrior: "We had to hope their [kicker] missed and our guy made it. We definitely have to do a better job all the way around, but we just played a good team today. They won 11 games this year, and you can't do that unless you're a good team. We expected it to be close, but not that close.''

If it's that close next week against the Patriots or Colts, chances are the Steelers (16-1) won't be making their first Super Bowl run since 1995 -- the one that has been highly anticipated in these parts for most of the second half of the season. Instead they will be dissecting the series of factors that led them to losing their fourth AFC title game at home in five tries under Cowher.

Was Saturday a wake-up call for the Steelers, or a preview of next week's fate? We have to wait another seven days to find out.

"This was terrible today,'' Roethlisberger said. "As a team, we need to definitely step it up. Everybody in the locker room knows that. The game that we played out there today is not going to cut it.''

At least of that much we're sure about these Steelers. The game might have been over, but for the first time all day, everyone in a Pittsburgh uniform was finally on the same page.

Don Banks covers pro football for SI.com.