Rob Burrow scored an Old Trafford stunner and set up Ryan Hall's decisive try as Leeds once again saw off St Helens to win the Grand Final.
Saints thought they would at last beat Leeds in Super League's showpiece at the fourth attempt when they came from 8-2 down at the break to lead 16-8.
But Brian McDermott's men turned it around with late tries from Brent Webb, Hall, Carl Ablett and Zak Hardaker.
Kevin Sinfield kicked six goals, but Burrow was man of the match.
The little scrum-half, who has controversially been used from the bench for much of the season by coach McDermott, proved a clear winner of the Harry Sunderland Trophy, picking up 100% of the vote.
And that made Burrow, who was also voted man of the match in the first of Leeds' four Old Trafford wins over Saints in 2007, the first man to receive that honour in a Grand Final.
But it was also a triumph for McDermott, the first English coach to get his hands on the trophy since Brian Noble in 2005, as Leeds equalled Saints' record of five Super League wins by handing the opposition a fifth straight final defeat.
After enjoying four Grand Final victories between 1999 and 2006, Saints have now lost four times to Leeds at Old Trafford, with last year's 22-10 defeat by Wigan sandwiched in bertween.
All the previous Grand Final contests between these two big rivals had been table-topping clashes. And, after an unsettled season, despite their improved form since losing in the Challenge Cup final to Wigan at Wembley six weeks ago, Leeds were considered second favourites for this meeting between third and fifth.
But the ominous outlook at kick-off time for Saints was the state of the Manchester weather.
A day of rain had left a slippery, sodden pitch - and the sort of conditions that the Rhinos exploited to the full on their three previous victorious Old Trafford meetings with the Merseysiders.
Leeds twice nearly exploited their early dominance, an interception break from near his own line down the middle by Brett Delaney only ending when he ran out of steam, before Hall's burst down the left ended with a loose pass.
It took until the 25th minute to register the first points on the board when Jamie Peacock was adjudged to have interfered with Lee Gaskell at the play-the-ball, Jamie Foster kicking the penalty.
But Leeds were level within three minutes when Saints were similarly penalised - and Sinfield slotted a 35-metre penalty.
Then, on 33 minutes, came the first moment that set Old Trafford alight as Burrow, receiving on the halfway line, dipped his diminutive frame under the first tackle that came at him before magically weaving his way on a 50-metre run past four more Saints players to go under the posts for one of the great Grand Final tries.
It looked as if Saints might get back on level terms within five minutes of the restart when Andrew Dixon - a scorer in last year's final - thought he had got over in a scramble close to the posts, only for a much-delayed video decision to rule that he had knocked on as he slid towards the line.
But, just minutes later, winger Tommy Makinson earned a more controversial verdict with an even messier try when, with Leeds full-back Webb trying to guide a grubber kick out of play, the Saints winger clearly got downward pressure on the ball, video ref Ben Thaler overlooking the fact that, split-seconds earlier, he had touched the ball with his outstretched fingertips.
To the delight of Saints fans and indignation from the Leeds contingent, Foster added the extras to tie it up again at 8-8 and, within five minutes, Saints were in again through centre Michael Shenton close to the right corner.
Foster missed the conversion but quickly atoned with two penalties - one from the halfway line - to give Saints an eight-point cushion going into the final quarter.
But an elbow injury to Shenton coming on top of the loss of joint captain Paul Wellens, with a recurrence of an Achilles injury, seemed to disrupt Saints. And Leeds were back to within two points on 64 minutes when Webb sneaked over on the left, Sinfield kicking the goal.
It was all square again at 16-16 four minutes later when Sinfield's 45-metre penalty sailed between the posts.
Then came Burrow's second major intervention as another dazzling run by the little number seven set up Hall to go in at the corner for his 32nd try of the season.
Late efforts from Ablett and Hardaker, both converted by skipper Sinfield, followed to ice the cake on Leeds' fourth - and most unlikely - Super League win in five years.
St Helens: Wellens; Makinson, Shenton, Meli, Foster; Gaskell, Lomax; Graham, Roby, Puletua, Wilkin, Soliola, Clough.
Replacements: Moore, McCarthy-Scarsbrook, Wheeler, Dixon.
Leeds: Webb; Jones-Bishop, Hardaker, Ablett, Hall; Sinfield, McGuire; Leuluai, Buderus, Peacock, Jones-Buchanan, Delaney, Clarkson.
Replacements: Burrow, Lauitiiti, Bailey, Kirke.
Referee: Phil Bentham (Warrington).