Leinster reached their first Heineken Cup final by sensationally routing defending champions Munster 25-6 before a record-breaking crowd at Croke Park in Dublin on Saturday evening.

Written off before the game, Leinster shocked their provincial rivals with their defensive excellence, impressive composure and sheer will to win, and proved the worthiest of winners.

Michael Cheika’s men scored three fine tries, too. After working their way into a 6-3 lead with a drop goal from Felipe Contepomi, who later went off injured, and a penalty from Jonathan Sexton, Leinster took command of the game when Gordon D’Arcy slid over just after the half hour after being put clear by Isa Nacewa.

A second penalty of the half from Ronan O’Gara meant that Munster only trailed by five at the interval (6-11) but Leinster landed a telling psychological blow when Luke Fitzgerald streaked over just after the restart.

Munster tried valiantly to rally but they could find no way through the wall of navy and blue placed before them and Leinster sealed the most significant and symbolical victory in their history when their talismanic centre Brian O’Driscoll conjured up an intercept try on 62 minutes.

Going into the game, Leinster’s hopes of victory had been all but dismissed. It was easy to understand why. They had been comprehensively beaten in their two previous meetings with Munster this season, in the Magners League. In addition, the last time that Michael Cheika’s men had faced Munster in the semi-finals of the Heineken Cup they had suffered a humiliating 30-6 defeat.

But Leinster put the ongoing pain of that loss to good use, using it as a source of motivation rather than fear.

Contepomi had suffered more than most that day in Lansdowne road three years ago but, in spite of a somewhat nervy opening, in which he missed a penalty and sliced a clearance horribly into touch, he inspired those around him in the opening quarter.

His composure and temperament have betrayed him many times before but he was, like Leinster, in no mood to buckle this time around and he edged Leinster ahead by nonchalantly lofting over a drop goal 16 minutes in.

Criminally, Leinster handed the initiative to Munster just moments after the restart. Cian Healy was guilty of a body on Ian Dowling in midfield and that resulted in not only a yellow card for the young prop but also three easy points for O’Gara.

Leinster, though, kept coming – even with 14 men – and deservedly reclaimed the lead on 26 minutes with a penalty. Contepomi should have been the man to take it but it was instead Jonathan Sexton, the fly-half having been drafted into the fray because of game-ending – and possibly season-ending – knee injury to Contepomi.

Indeed, the Argentine was helped from the field not only in agony, but in tears, aware that his Leinster career, which is set to come to an end this summer when he makes the move to Toulon, had probably been brought to a horribly cruel premature end.

As exemplified by his confidently-struck penalty, though, Sexton was not about to let all of the early good work from Contepomi go to waste.

Indeed, he very nearly created a try for Fitzgerald with a clever cross-field kick as Leinster continued to press.

When restored to their full complement, they finally struck. Unsurprisingly, O’Driscoll played a key role, drawing two men towards him before releasing Nacewa, who pierced the Munster line with the aid of a magnificent line.

Leinster’s utility man blazed into the Munster 22 before spinning a measured pass out to the left to the supporting D’Arcy, who had the pace and the momentum to propel himself over the whitewash.

Sexton failed to convert, allowing O’Gara to draw Munster to within five points with a penalty five minutes before the break but there was no mistaking the fact that the defending champions were wobbling.

With 15 minutes in which to regroup, one expected a Munster backlash at the start of the second half. However, Leinster did not even give them time to start one, silencing The Red Army once more with a try from Fitzgerald.

Again it was a classic Leinster score, the men in navy and blue working it wide swiftly through the hands of Nacewa and O’Driscoll before Horgan deftly flicking the ball into the path of Leinster’s young Lion. Fitzgerald still had Paul Warwick in front of him but the winger stepped inside the full-back with consummate ease to score a wonderful try.

Munster were crumbling. Unforced errors were creeping in all over the pitch. They raised themselves for one last onslaught but after a period of sustained pressure, O’Driscoll stepped out of the line to intercept a loose from O’Gara before streaking clear to score under the posts.

Sexton’s conversion from right in front of the posts put 19 points between the side. Munster have become synonymous with Heineken Cup miracles but as had been evident perhaps from the very early in the game this was not to their day.

Leinster, for so long criticized for their mental resolve, their bottle, had finally stood up and been counted.

Munster: Paul Warwick; Doug Howlett, Keith Earls, Lifeimi Mafi, Ian Dowling; Peter Stringer, Ronan O'Gara; Marcus Horan, Jerry Flannery, John Hayes; Donncha O'Callaghan, Paul O'Connell; Alan Quinlan, David Wallace, Denis Leamy.

Replacements: Denis Fogarty, Tony Buckley, Mick O'Driscoll, Niall Ronan, Mike Prendergast, Barry Murphy, Denis Hurley.

Leinster: Isa Nacewa; Shane Horgan, Brian O'Driscoll, Gordon D'Arcy, Luke Fitzgerald; Felipe Contepomi, Chris Whitaker; Cian Healy, Bernard Jackman, Stan Wright; Leo Cullen, Malcolm O'Kelly; Rocky Elsom, Shane Jennings, Jamie Heaslip.

Replacements: John Fogarty, Ronan McCormack, Devin Toner, Sean O'Brien, Simon Keogh, Jonathan Sexton, Girvan Dempsey.