Leeds gave coach Tony Smith the perfect send-off with a second Grand Final triumph in four years to end St Helens' 100 percent record at Old Trafford.

Smith, who goes full-time with Great Britain next week, ended his four-year stint in fairytale fashion as the Rhinos upset the odds to wrest the Super League crown from their arch-rivals in front of a bumper 71,352 crowd.

Leeds, who finished a point behind their opponents at the end of the regular season, led throughout a compelling final, running in five tries to one to deny Saints a second consecutive clean sweep.

Leeds scrum-half Rob Burrow, one of the "little men" identified as a threat by Saints coach Daniel Anderson, came up with a man-of-the-match display but the Rhinos were also indebted to the barnstorming runs of forwards Jamie Peacock and Gareth Ellis which laid a solid platform for the emphatic win.

St Helens trailed 8-0 after 18 minutes but briefly threatened to take the spoils on the back of an impressive opening from the talismanic Sean Long, whose appearance was only confirmed an hour before kick-off.

Long fluffed an early chance to open the scoring when he was wide with a simple enough penalty but he showed little sign of nerves or the injuries that have plagued him over the last two months with a series of wonderfully-judged kicks which pinned Leeds back in their own 20-metre area.

Long's half-back Leon Pryce came up with the first handling error after 22 minutes of cat-and-mouse play and that was the signal for the game to open up.

Leeds skipper Kevin Sinfield put his side in front when Saints were caught offside on 15 minutes, thus becoming the first Leeds man - and only the second in Super League after Andy Farrell - to play and score in every match in a season.

That gave the Rhinos the encouragement to put together a wonderfully intricate passing move, honed no doubt on the training pitch, with McGuire and Sinfield working the ball out to full-back Brent Webb, who took an inside pass from winger Scott Donald to claim his 24th try of his inaugural Super League season.

Sinfield's conversion made it 8-0 but the introduction of newly-crowned Man of Steel James Roby, not for the first time this year, put a new complexion on the match.

He had been on the field only five minutes when he got on the end of a superb break by Long which was carried on by Lee Gilmour to skip out of Lee Smith's attempted last-ditch tackle to crash over for a score reminiscent of his crucial try in Saints' Challenge Cup win at Wembley.

This time Long put over the goal to cut the deficit to just two points but that was as good as it got for Anderson's men.

Leeds missed a glorious chance 10 minutes before the break when McGuire re-gathered his own delicate chip through the Saints defence but saw his second kick roll agonisingly into touch with Donald in hot pursuit.

But the game was swiftly taken away from St Helens as Rhinos took a firm grip with two tries in a three-minute spell early in the second half.

Second-row substitute Ali Lauitiiti tore through the Saints defence with a powerful angled run to the corner and then quick hands from Webb and Keith Senior released Donald, who beat Paul Wellens on the outside to finished off a classic 60-metre move.

Sinfield's third goal made it 18-6 and Burrow put more daylight between the sides with a 57th-minute drop goal.

St Helens had to force the game and came up with yet more errors and they were ruthlessly punished as Leeds turned what had been an even contest into something of a rout.

Smith outjumped Francis Meli to collect McGuire's towering kick and touch down and ever-present second rower Jamie Jones-Buchanan forced his way past a tiring defence in the last minute to score his fifth try of the season.

Sinfield took his goal tally to six from seven attempts and then dedicated the win to his coach and a former Leeds legend, Jeff Stevenson, who passed away earlier in the day.