Glenstal march on
Glenstal became the first side to reach the semi-final thanks to a splendid second-half performance.
With no score in the first half and few chances created, fears were growing that a scoreless draw might be the outcome, which would have meant a penalty shoot-out.
But dominance by the Glenstal forwards in the second half paved the way for four tries.
The crucial first try came seven minutes into the second half when Andrew Hogan's break led to Michael Gilbride touching down in the corner. Tiernan Ryan got the second try, with Hogan adding the extras.
Replacement Daniel Okeke kept Ardscoil hopes alive with a try which Adam McNamara converted.
Brian Leonard set up Ronan Hanly's try in the corner and an intercept try by Hogan which he also converted decided the issue.
Glenstal Abbey - R Quinn; R Hanly, E Alyward, A Hogan, R Woodcock; C Dooley, B Leonard; D Moriarty, E Fitzgerald, M Downing; T Ryan, W Twomey; B Fitzgerald, M Gilbride, P Mulligan. Reps: M Lynch, D Hyland, C Butler, K Floyd, D Butler, M Esmonde, S MacKeown, J Collins, J Ryan, C Kennedy.
Ard Scoil Ris - M Gaule; D O'Byrne, K Dineen, J Ward Murphy, G Hanrahan; A McNamara, E Sherlock; E Healy, S Cleary, F Lyons; M Daly, L Barry; J Hadaker, R Barry, O Czyszczon. Reps: A Tobin, D Dwane, G Power, J Leahy, D Okeke, C McCloskey, G Higgins, N Robertson, P Hyland, J McMahon, B Doherty.
Ardscoil Ris 7