The eventual winners of this semi-final were always going to be anointed as outstanding favourites to win the title, and it was Blackrock who emerged victorious from an enthralling tussle.
There was a 'thou shall not pass' attitude taken by both sets of defences as they put their shoulders into the tackle and embraced the breakdown challenge. The holders, St Michael's, held a slight edge, openside Oisin Dowling operating authoritatively at the line-out, and their centres Jack Kelly and James Hickey causing problems through the middle.
It all suddenly burst into life when Blackrock raided down the right flank off a twisting scrum, full-back Steven Kilgallen ghosting through from halfway via a dummy option. Scrum-half James McGowan tagged on the conversion in the 20th minute.
The move triggered increased confidence, reflected in centre Tommy O'Brien's nifty offload to wing Matthew O'Callaghan.
But, the Sky Blues were soon back on the counter through Kelly and flanker Robert Duffy. When the 'Rock front-row could not keep up their end of a scrum, left-wing Tom Donnellan made it 7-3 on the break.
Blackrock second-row Caelan Doris appeared to strike a decisive blow when he charged down scrum-half Peter O'Beirne's kick and showed no little skill in controlling a bobbling ball for a try in the 34th minute for a 12-3 and two-score lead.
An indiscretion at scrum-time provided McGowan with a shot at goal from 36 metres. He had the distance and the accuracy.
There was still time for a St Michael's surge. Captain Kelly almost got away. Fly-half Harry Byrne's kicking was effective. But, they could not crack 'Rock's defence and left-wing Nick Gleeson found the time and space to seal it in injury-time.
Blackrock – S Kilgallen; M O'Callaghan, G Mullin, T O'Brien, N Gleeson; C Dean, J McGowan; H Egleston, E Olden, E Burns, N Marshall, C Doris, R Dunne, J Mion (capt), H Burke. Reps: R Mouatt for Burns (39); A Murphy for Burke (51); B Nolke for Dunne (62); B Layden for Gleeson, P O'Reilly for Dean, C Connolly for Olden, T O'Hagan for Egleston, L Gaffney for McGowan all (64).
St Michael's College – M Heaney; C Carey, J Kelly (capt), J Hickey, T Donnellan; H Byrne, P O'Beirne; R Kelleher, T Glynn, S Griffin, J Kennedy, M O'Donahoe, R Duffy, O Dowling, B Fitzpatrick. Reps: H McIntyre for Carey (40), A Connolly for O'Donahoe (40); T Killeen for O'Beirne (62) mins; M Kennedy for Glynn (64).
Ref – G Glennon, Leinster Branch.