Cannot play media. Sorry, this media is not available in your territory.
Highlights: St Helens 16-24 Leeds Rhinos
Leeds retained their Super League crown and ruined Daniel Anderson's farewell game for St Helens by winning a rain-soaked Grand Final in Manchester.
Saints opened the scoring with a James Graham try but underdogs Leeds led 12-6 at the break thanks to touchdowns from Lee Smith and Ryan Hall.
Matt Gidley went over to draw the sides level at the start of the second half.
But two Danny McGuire tries ensured Ade Gardner's 31st touchdown of the season for Saints was to no avail.
St Helens, who had crushed the Rhinos 38-10 just a fortnight ago, broke the deadlock with a fantastic try inside six minutes - and Sean Long was the architect.
McClennan delighted with Leeds spirit
After being pinned back by Leeds in the opening exchanges, they carved through the Rhinos defence when Long set Lee Gilmour free with a well-timed inside pass around the halfway line.
Gilmour then swapped passes with Paul Wellens before offloading to newly-crowned Man of Steel Graham, who, with no-one in front of him just five yards from the line, had the simplest of tasks to score the first try of the night.
Long stepped up to kick the conversion from just to the right of the posts to make it 6-0.
The Rhinos had looked the dominant side up until then and refused to be knocked out of their stride by the setback.
They continued to heap pressure on Saints, forcing them into a number of errors, before eventually drawing level on 24 minutes.
A great offload from the bandaged Jamie Jones-Buchanan, who just a few minutes had blood gushing from a wound high on his forehead after colloding with the knee of a team-mate, found stand-in full-back Smith, who brushed off several tackles to slide over on the left.
Leeds skipper Kevin Sinfield duly tied the scores with a tricky conversion.
Both sides were making handling errors in the wet conditions, but Saints looked uncharacteristically ruffled and disorganised.
It was from a penalty, conceded by Saints for not standing square at the play-the-ball, that Leeds eventually took the lead on 36 minutes.
Sinfield picked out Keith Senior with a long, floated pass, but the centre flicked it on to Hall rather than catch it himself.
Hall still had plenty of work to do to reach the line, but a clever kick took him past Willie Talau and allowed him to touch down by the right-hand corner flag.
Sinfield extended the lead by landing the conversion the ball going over via the left upright.
Leeds deserved their half-time lead, but, after a rollicking by Anderson, Saints began the second half with a bang.
The Rhinos celebrate as the final hooter sounds at Old Trafford
A high kick by Long was patted back by Gardner for Gidley to power his way over, with Long curling home the conversion to tie the scores again.
Leeds were unfazed by the poor start following the interval and went ahead for a second time when Sinfield's deft kick off his weaker left foot split open the Saints defence and allowed McGuire to touch down under the posts.
With Sinfield adding the extras, Leeds once again had a six-point advantage with 50 minutes gone.
That lead was cut to just two points just eight minutes later when Gardner dived over in the right corner after taking James Roby's pass, with Long failing to add the extras.
But it was up to eight points when McGuire darted over for his second try of the night after a high Sinfield kick had caused mayhem in the Saints defence.
Francis Meli failed to collect it cleanly and McGuire shrugged off one tackle before sidestepping another defender to go over under the posts, making the conversion an easy one for Sinfield.
Any chance Saints had over hauling their way back into the game was thwarted by a series of errors and some resolute Leeds defending.
But the Rhinos deserved their win as they became only the second team - after Saints - to successfully defend their Super League title.
Smith walked off with the man-of-the-match award to put himself in the frame for an England call-up ahead of the World Cup.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.