MVP Hines Ward (left) and Jerome Bettis had cause to celebrate

Seattle had the better of the first half, but ended it 7-3 down after a controversial touchdown by Steelers quarterback Ben Roethlisberger.

Willie Parker then ran in a 75-yard score, setting a Super Bowl record.

And although Jerramy Stevens gave the Seahawks hope, Antwaan Randle El sealed the win by executing a brilliant trick play to MVP Hines Ward in the endzone.

Snapwatch: All the action as it happened

It brought about career-defining moments for veteran running back Jerome Bettis - who retired immediately afterwards - and for long-serving coach Bill Cowher, neither of whom had won a Super Bowl before.

And the Steelers won their fifth season finale, tying Dallas and San Francisco for the most in the NFL, while Roethlisberger became the youngest winning quarterback at 23.

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Pittsburgh had looked like a team of destiny in the play-offs, beating the Cincinnati Bengals, Indianapolis Colts and Denver Broncos to become first sixth seed to reach the Super Bowl.

And they were favoured by good luck early on when Seattle's Darrell Jackson thought he had scored the first touchdown, only for a debatable pass interference call to intervene.

A Josh Brown field goal from 42 yards gave the underdogs a deserved lead, but dropped passes and stray feet placed out of bounds then cost them dear.

Pittsburgh, who enjoyed most of the crowd support, failed to record a first down until the second quarter.

But suddenly they sparked into life, Roethlisberger connecting with Ward to reach the Seattle three-yard line.

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Hometown hero Bettis spurned two chances to convert before Roethlisberger made a desperate dive for the line and was awarded a touchdown when it looked questionable that he had crossed the line.

The Rolling Stones served up the half-time musical fare and might have been singing about Seattle when the old classic "I can't get no satisfaction" bounced around Ford Field.

And, sure enough, on the first drive of the second half, missed tackles allowed Pittsburgh's pacy Parker to complete the longest touchdown run in Super Bowl history.

Photos: Super Bowl XL in Detroit

Roethlisberger handed the Seahawks a lifeline when he carelessly threw an interception to Kelly Herndon, who ran the ball back for 70 yards.

And Seattle quarterback Matt Hasselbeck - who impressed in his losing effort - rifled a touchdown pass to Stevens to reduce the deficit to four points.