Leinster (11) 25
D'Arcy, Fitzgerald, O'Driscoll Con:
Sexton 2 Drop-goal:
Munster (6) 6
Brian O'Driscoll's scores Leinster's third try at Croke Park
Leinster produced an epic display to hammer holders Munster into submission in a remarkable Heineken Cup semi-final at Croke Park.
Few gave Leinster a chance of winning but their resolve proved too much for Munster in front of a world-record 82,208 attendance for a club match.
Gordon D'Arcy's first-half try helped Leinster lead 11-6 at the interval.
Luke Fitzgerald's try increased the strangehold and Brian O'Driscoll's breakaway score finished off Munster.
The contest started at a ferocious pace with both teams putting in big early hits.
Felipe Contepomi missed the first scoring chance from a kickable penalty and the unpredictable Argentine endured a nervy few moments as a woeful pass in midfield put his defence under pressure with O'Driscoll's attempted clearance being charged down.
Tempers then flared after D'Arcy slapped out at Keith Earls, who pipped the Leinster and Ireland centre for a place in the Lions squad.
However, Earls reacted in the best possible fashion by producing a stunning break into the Leinster 22 after a slip pass by the busy Lefeimi Mafi and only a massive hit by Rocky Elsom on Ian Dowling averted the danger.
Contepomi regrouped from his early nerves to stroke over a delicious drop-goal in the 16th minute but O'Gara levelled two minutes later after Cian Healy's silly sin-binning for a late tackle on Dowling.
Elsom was leading Leinster's charge and his break had the Munster defence backpedalling furiously in the 25th minute.
However, Leinster then suffered a blow when Contepomi was forced to depart after appearing to twist his knee on the immaculate Croke Park turf.
Sexton was the replacement and his first action was to coolly knock over a penalty to restore Leinster's lead.
Munster's Marcus Horan attempts to stop a charging Rocky Elsom
Any suggestion that Leinster were going to be streamrollered as in the 2006 semi-final was dispelled when D'Arcy slid over for a tremendous try in the 31st minute after Isa Nacewa's burst into space in midfield.
Sexton missed the conversion but Leinster were 11-3 up and largely controlling the exchanges.
The outstanding Elsom gifted O'Gara three points four minutes before the interval after a cynical obstruction on Doug Howlett.
A big Munster effort would have been expected after the break but instead it was Leinster who struck a decisive blow in the 44th minute.
Once again, Nacewa was involved in the flowing move and another of his perfect passes reached a charging Fitzgerald who broke through Paul Warwick's feeble attempt of a tackle.
Sexton added the conversion from near the touchline and suddenly the lead was 12 points.
Inevitably, Munster responded with a bout of sustained pressure before the hour mark but Leinster refused to yield with the tremendous Nacewa producing a great tackle to prevent a Howlett try.
As Munster became increasingly frustrated, Lions selection Alan Quinlan appeared to eye-gouge Leinster's Leo Cullen although the match officials took no action against the flanker.
Leinster's supporters were in delirium in the 61st minute as O'Driscoll ran 70 metres to touch down under the posts after he had nipped in ahead of Paul O'Connell to intercept a looping O'Gara pass.
Munster produced some late huff and puff but the ball was too slow to trouble an astonishingly resolute Leinster defence.
After all the jibes about Leinster's folding when it really mattered, this was one sweet victory for Michael Cheika and his troops.
Nacewa; Horgan, B O'Driscoll, D'Arcy, Fitzgerald; Contepomi, Whitaker; Healy, Jackman, Wright, Cullen (capt), O'Kelly, Elsom, Jennings, Heaslip.
Dempsey for Fitzgerald (59), Sexton for Contepomi (25), Fogarty for Jackman (62), O'Brien for Jennings (74).
Not Used: McCormack, Toner, S. Keogh.
: Healy (16).
Warwick; Howlett, Earls, Mafi, Dowling; O'Gara, Stringer; Horan, Flannery, Hayes, O'Callaghan, O'Connell (capt), Quinlan, Wallace, Leamy.
Murphy for Warwick (66), D Hurley for Earls (78), Prendergast for Stringer (74), Fogarty for Flannery (71), Buckley for Hayes (68), O'Driscoll for O'Callaghan (74), Ronan for Leamy (66).
: Nigel Owens (WRU).