St. Mary's College came from behind to beat Garryowen, a team currently ranked seven places above them in Division One, and secure a spot in April's inaugural AIB Cup final.
AIB CUP: SEMI-FINAL: Saturday, February 25
GARRYOWEN 14 ST. MARY'S COLLEGE 23, Dooradoyle
Scorers: Garryowen: Try: Paul Neville; Pens: Conor Kilroy 3
Mary's: Tries: Keith Douglas, Cillian O'Byrne; Cons: Mark McHugh 2; Pens: Jonathan Sexton, McHugh 2
Former schoolboy prop Cillian O'Byrne ensured a place in the April 8 decider for Mary's as his 80th-minute try set up a famous nine-point win for the visitors at Dooradoyle.
O'Byrne ploughed over and Connacht's Mark McHugh added the conversion in a climatic finish after Garryowen had edged the first half 8-6. There were still five minutes of injury-time remaining after O'Byrne's effort but Mary's, having already accounted for Greystones and Terenure College in their Cup run, held on.
Mary's captain John McWeeney, the former Leinster and Ireland winger, said afterwards: "We're delighted to win. Having come down here to Limerick in previous seasons and lost a good few times, it's nice to put one over Garryowen.
"We decided that we would treat it as a "one-off" game - just go and play it as it comes and it worked out for us.
"(Having been 8-6 down at half-time) we came out and just focused on getting the next score. I don't mind who we get in the final, honestly, we're just happy to have made it through and it's something for everyone at the club to look forward to now."
Conor Kilroy traded early penalties with Mary's young fly half Jonathan Sexton, who came off the bench for the Ireland Under-21s the previous night, and the hosts led 8-6 at the interval. Flanker Paul Neville burrowed over for the Limerick side's try midway through the opening half.
However, Mary's snapped back to lead 16-14 courtesy of a converted try from centre Keith Douglas, who made the most of a weak tackle from Garryowen midfielder Paul Devlin, and a McHugh penalty. Home fly half Kilroy had added two penalties to his side's half-time tally.
McHugh, also playing in midfield, was central to the win as he kicked ten points, including two penalties.
But the defining moment came when all 16st 5lbs of O'Byrne was driven over the line in a climatic finish.
GARRYOWEN: A Finn; F Daly, K Hartigan, P Devlin, C O'Boyle; C Kilroy, G Hurley; R Brosnan, D Varley (P Humphreys half-time), R Laffan (N Hartigan 50), M Melbourne, D Sheehan, P Neville, A Kavanagh (J O'Sullivan 60), P Malone (capt).
ST MARY'S: P Brophy; R Smyth, K Douglas, M McHugh, J McWeeney (capt); J Sexton, J Kilbride; C O'Byrne, P Smyth (O McCormack 68), P Collins, E Keane, W Duggan (M Donnellan 73), P Nash, A Copeland, H Gervais (B O'Donoghue 73).
Referee: Donal Courtney (IRFU)