It means that the inaugural Magners League Grand Final will now be between Leinster and the Ospreys at the RDS on Saturday, 29 May (kick-off 6.30pm).
A try from Rob Kearney and 11 points from the boot of Jonny Sexton made it four wins in a row for Leinster over their arch-rivals. All Munster#s points came from skipper Ronan O'Gara.
Leinster won the right to host the Grand Final because they finished on top of the regular Magners League table. It means they can expect another sell-out crowd of 19.750 when the top placed Welsh region arrive in the Irish capital in two weeks time.
It will be a special occasion for Leinster coach Michael Cheika as he takes charge of the side for the last time before heading to France to take over the coaching reigns at Stade Francais Paris.
It will also be an emotional night for two Leinster stalwarts, lock Malcolm O'Kelly and full back Girvan Dempsey, who are hanging up their boots after distinguished service to club and country. It will also be a final outing for the Ospreys' former New Zealand No8 Filo Tiatia before he retires.
Leinster beat the Ospreys 18-11 at the Liberty Stadium at the start of the season and they completed the double with a 20-16 triumph at the RDS on 16 April. Whichever team wins the battle between the Heineken Cup semi-finalists and quarter-finalists will become the first team to win the Magners League title three times.
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