This game exploded into life from the moment Leinster hooker Ethan Baxter got around John Hurley for an opening minute try converted by centre Mick O’Gara.
The Munster inside centre Hurley appeared to take this personally as he thundered onto a smart ball from fly-half Ryan O’Sullivan to reach for the line in the third minute and converted as well.
The next time Hurley came hard and straight, number eight Ed Brennan was there to stop him in his tracks.
This was the first of a number of hard hits delivered to show scores would be harder to come by as the game was carried out between the 22s.
Leinster out-half Ben Watson’s grubber forced full-back to Mark McLoughlin to concede a lineout.
A comedy of errors almost allowed Leinster to benefit from a charge-down and their tight-head Thomas Clarkson’s leg drive put them close to the line.
From a rock-solid scrum, Brennan carried well, Jody Booth added his weight to the argument and left wing Andrew Smith knifed between centres Hurley and Jamin Hoffman for O’Gara to convert.
Once again, Leinster were generous from the restart as out-half Watson was blocked by captain Cian Hurley, who had the presence of mind to regather and finish to make it 14-12 from the conversion in the 25th minute.
Munster were not able to hold their discipline in moving up offside as Leinster swung the ball left and right, O’Gara knocking over three points from in front of the sticks close to half-time.
O’Gara was back on point for three more before Munster replacement Jack Delaney swiftly made it for 20-15 in the 40th minute.
A sharp line from centre Hoffman had to be closed down by Leinster full-back Sam Dardis.
Then, flanker Booth hit the line at pace and offloaded beautifully for lock Daniel Beggs to pick up Leinster’s third try, converted by O’Gara in the 47th minute.
It should have been a building block. Instead, Munster rolled up their sleeves at the maul and out-half Delaney followed up his own kick to ground the ball and convert from the right for 27-22 in the 54th minute.
The mistakes were piling up as the game loosened up. Leinster attacked from deep, through full-back Dardis, for their wing Max O’Reilly to claim their fourth try converted by O’Gara.
Leinster replacement Gavin Dowling was binned for illegal work at a breakdown and Munster looked odds-on to score from a maul until captain Cian Prendergast ruined it for a turnover.
And that was the game.
At Donnybrook – LEINSTER 34 (E Baxter, A Smith, D Beggs, M O’Reilly try each; M O’Gara 2 pens, 4 cons); MUNSTER 22 (J Delaney try, pen con; J Hurley try, con; C Hurley try).
Leinster: Sam Dardis (Terenure); Max O’Reilly (St Gerard’s), Tom Maher (Blackrock), Mick O’Gara (Pres Bray), Andrew Smith (St Michael’s); Ben Watson (St Gerard’s), Adam McEvoy (St Mary’s); Conor Duff (Clongowes), Ethan Baxter (St Gerard’s), Thomas Clarkson (Blackrock), Cian Prendergast (Newbridge, Capt), Daniel Beggs (Clongowes), Jody Booth (St Michael’s), Anthony Ryan (Clongowes), Ed Brennan (Blackrock).
Replacements: Ben Murphy (Pres Bray) for McEvoy ht; Cian Duffy (Blackrock) for Duff 40 mins; Gavin Dowling (Clongowes) for Beggs 60 mins; James Reynolds (CBC Monkstown) for Maher 65 mins.
Munster: Mark McLoughlin (PBC); Jack Hunt (Rockwell), Jamin Hoffman (Crescent), John Hurley (Crescent), Ronan Quinn (Glenstal); Ryan O’Sullivan (Midleton), Oisin Mangan (Rockwell); Conor Fitzgerald (Crescent), Aaron Hennessy (The Arya Project Scarriff), Mark Donnelly (CBC), David McCarthy (PBC), Eoin Quilter (PBC), Cian Hurley (CBC, Capt), Mark Crowe (St Munchin’s), Alex Kendellan (PBC).
Replacements: Jack Delaney (Crescent) for O’Sullivan 27 mins; Evan Sheehan (St Munchin’s) for Fitzgerald, Daniel Okeke (Ardscoil Ris) for Quinn both ht; Jack Riordan (CBC) for Mangan 38 mins; Kieran O’Shea (Castletroy) for Hennessy 44 mins; Jude Pendijito (St. Munchin’s) for J Hurley 45 mins; Timmy Duggan (Crescent) for McLoughlin 50 mins; Tommy Downes (CBC) for Hoffman 62 mins.