It was billed as the "Last Stand" and we were served up a rip-roaring game of such intensity to do justice as the curtain fell at Lansdowne Road as we know it for the last time.
In the end it was Leinster who were still standing, reducing Ulster's lead at the top of the Magners League table to three points with a deserved victory which also denied the visitors a losing bonus point in front of a record Magners League crowd of 48,000.
Ulster had threatened to cause an upset at the break when three penalties and a drop-goal by Paddy Wallace had given the visitors a 12-5 lead.
But with the conditions in their favour in the second period, Leinster dominated the remainder of the contest and further touchdowns by Jamie Heaslip and Owen Finegan, after a first-half injury-time try by Denis Hickie, took the game away from the champions.
The opening was a nervy, tense affair. A huge tackle by Roger Wilson and Simon Best on Shane Horgan, as he attempted to step inside, set the early tone for the visitors.
But after the Ulster pack had rumbled a maul into a promising position, a couple of mistakes allowed Leinster to seize the momentum.
First David Humphreys was unable to hold a wild pass by Isaac Boss and then the Ulster out-half mis-struck a Garryowen attempt.
And as the home side turned up the pressure, a clearance kick by Mark Bartholomeusz went straight to Brian O'Driscoll in the Ulster 22 and it took some desperate scrambling defence to clear their lines.
The visitors then suffered a massive blow when Humphreys was forced to retire, having taken a heavy blow at a ruck; a desperately disappointing finish to his Lansdowne Road career.
But while Leinster had the early initiative, the home side were also guilty of allowing errors to undermine their game.
First O'Driscoll couldn't hold a wide pass, then a scorching blindside break by Gordon D'Arcy, who linked with Jamie Heaslip, ended up with the centre knocking-on with the line at his mercy.
And having weathered the storm, the visitors gradually gained confidence from having kept their line intact and after a period of composed recycling, it was Ulster who took the lead when Paddy Wallace, on for Humphreys, slotted a 22nd minute penalty, after former Ulster prop Ronnie McCormack had strayed offside.
Leinster pushed hard from the restart but a golden opportunity was squandered by the visitors when after Matt McCullough had intercepted in the midfield, a huge overlap was spurned when the ball squirted loose and Boss lost possession.
But the edginess in Leinster's play cost them when Horgan knocked-on from Bartholomeusz's high ball and Ulster were awarded a penalty from the scrum which Wallace slotted superbly in the gale to double the score in the 22nd minute.
And Ulster's hopes heightened when, after a blazing counter-attack which saw Tommy Bowe almost barge his way through, Wallace slotted his third penalty in the 36th minute.
Ulster desperately needed a solid restart to protect their lead, but the contest sparked into life when Jamie Heaslip was able to gather a loose ball and go charging into the Ulster 22.
After several blue tidal waves, Hickie tapped a quick penalty in front of the posts, but Stephen Keogh knocked-on over the line after a tackle by Trimble.
Leinster would not be denied however and after Sexton had gone close, the pressure told when, after O'Driscoll and Keogh had made the hard yards, Horgan fed Hickie to score the game's opening try in first-half injury time.
Yet there was still another twist in the half when, following and penalty kick to the corner by Ulster, Wallace banged over a superbly-struck drop-goal, after his tackle had turned over Keith Gleeson.
Seven points was a sizeable advantage for the visitors but it was not enough to stop Leinster pushing on to victory.
With the worst of the weather to contend with, Ulster spent almost the whole half defending.
Leinster reduced the deficit when, after Wallace missed a penalty to the corner and Neil Best lost possession, O'Kelly hacked through and Wallace's clearance kick went straight to O'Driscoll, who launched a ferocious attack.
When Ulster were caught offside, Sexton landed his first penalty in the 45th minute, to cut the deficit to four points.
The young Leinster out-half missed another attempt, but he quickly attempted to make amends with a surge into Ulster's half, after the visitors had once again coughed up the ball.
Ulster were continually undone by poor protection of the ball at the breakdown, but they were given hope when, after Wallace had gobbled up Horgan following his own high ball and Kieron Dawson had won possession on the ground in the Leinster 22, Denis Hickie was shown a yellow card for killing the ball.
Wallace could not convert however and Ulster wouldn't threaten again as Leinster ruthlessly set about overhauling the visitors.
D'Arcy should have scored when he dropped the ball with the line at his mercy, after a vicious high ball by Felipe Contemponi had forced a mistake by Trimble.
But the breakthrough eventually came when Owen Finegan barged over from close range in the 64th minute to nudge Leinster in front.
With Ulster unable to escape from their own half, Leinster turned the screw and when Heaslip raced over after Bernard Jackman had picked up a flip pass by O'Driscoll, it was game, set and match.
LEINSTER: R Kearney; S Horgan, B O'Driscoll (capt), G D'Arcy, D Hickie; J Sexton, C Whitaker; R McCormack, B Jackman, W Green, T Hogan, M O'Kelly, S Keogh, K Gleeson, J Heaslip. Subs: R Corrigan for McCormack (27), F Contepomi (62), O Finegan for Gleeson (51), K Lewis for Kearney (72), G Easterby for Whitaker (74), H Vermaas for Jackman (79).
YELLOW CARD: D Hickie (58-68)
ULSTER: M Bartholomeusz; T Bowe, K Maggs, P Steinmetz, A Trimble; D Humphreys, I Boss; B Young, R Best, S Best (capt), J Harrison, M McCullough, N Best, K Dawson, R Wilson. Subs: P Wallace for Humphreys (6), J Fitzpatrick for Young (64), N McMilan for Dawson (68), P McKenzie for Maggs (71), P Shields for Best (79), T Barker for Harrison (79).
LEINSTER SCORERS: Tries: D Hickie, O Finegan, J Heaslip. Cons: F Contepomi. Pens: J Sexton
ULSTER SCORERS: Pens: P Wallace (3). Drop-goals: P Wallace.
REFEREE: G Clancy (IRFU).