Young Munster suffered their third Ulster Bank League semi-final defeat in as many years as defending champions Clontarf proved too strong at Castle Avenue, winning 37-29.
Clontarf ran in six tries, including a brace from former Leinster winger Mick McGrath, to claim an eight-point success and move within 80 minutes of their third Division 1A title in four years.
The north Dubliners will face Cork Constitution in a repeat of last year's final at the Aviva Stadium on Sunday, May 7. Joey Carbery, one of Leinster's gallant heroes in Lyon today, was man-of-the-match in last May's thrilling 28-25 victory over Con.
This afternoon on their 4G pitch, it was McGrath who led the way, breaking through a ruck to score under the posts in the third minute with David Joyce converting.
With the scheduling clash with this weekend's British & Irish Cup final, the Cookies had to do without the likes of Dan Goggin, Cian Bohane, Robin Copeland and Gavin Coombes, but did at least have Fineen Wycherley, Calvin Nash and Abrie Griesel at their disposal.
One of Young Munster's leading performers this season, teenage out-half Alan Tynan, was in inspirational form early on, cutting through for a brace of first half tries. The Tipperary starlet danced through the 'Tarf defence and converted his seventh minute try to bring the visitors level, before he sniped over for a second early in the second quarter.
Crucially, Andy Wood's home side took advantage of a yellow card to score 10 points in the lead up to half-time, out-half Joyce landing a penalty and converting captain Ben Reilly's late score after a terrific break from flanker Tony Ryan.
A 17-12 interval deficit was suddenly 27-15 in the third quarter as Munsters, who had a 50th minute penalty from Tynan, dug deep to stay in contention. Either side of Tynan's kick, McGrath burst through for his second try and centre Conor O'Brien also touched down in the corner.
Bristol-bound hooker Jason Harris-Wright and current Leinster squad members Mick Kearney and Bryan Byrne were part of a strong Clontarf pack, the latter coming in for the final half-an-hour along with Connacht's Ivan Soroka.
That strength in depth proved too much for Munsters to handle, 'Tarf replacement Rob McGrath duly joining his brother as a try scorer on the hour mark and scrum half Mark Sutton acrobatically diving over in the corner for the sixth try late on.
The Cookies, in Gearoid Prendergast's first year as head coach, can hold their heads high as this was a proud and fiercely-committed performance from a youthful squad that is clearly going places. A penalty try in the final play supplemented a 72nd-minute converted score from current Ireland Under-20 international Jack Lyons.
Referee: Gary Conway (IRFU)