Captain Louis McDonough kicked a 64th-minute penalty to give Castleknock College a shock victory over Belvedere College in the Leinster Schools Senior Cup quarter-final at Donnybrook.
With 12 titles at this grade, Belvo were favourites to prevail in this contest.
They had recovered from a 12-point deficit to lead on the hour mark, before McDonough’s late intervention ensured the Jeremy Staunton-coached Castleknock claimed a major scalp.
After a line-out maul placed them on the front foot, Castleknock tighthead prop Ben Griffin held off a host of challenges for a try on three minutes.
McDonough’s conversion attempt was wide of the mark but Castleknock continued to dominate possession as the action progressed.
Following an extended spell inside the Belvo ’22’, the imposing Griffin powered over the whitewash for his second try. McDonough made no mistake on this occasion to fire Castleknock a deserved 12-0 cushion on the stroke of 15 minutes.
While Belvo inevitably grew into the game, they couldn’t find a breakthrough of their own before the interval.
However, the north Dubliners came to life on the restart.
At the end of an intricate move across the Castleknock line, lock Darragh Coan released Peter O’Farrell for a clinically-taken try with the conversion added.
This ramped up the pressure on Castleknock and when Griffin was sent to the sin-bin in the final-quarter, it served as a springboard for Belvo to edge in front. Loosehead prop Jonathan Sargent exploited space on the left-flank to touch down and Jed Tormey nailed a superb conversion to give the Great Denmark Street outfit a slender cushion.
They were expected to push on from this point, but Castleknock had other ideas. At a distance of 30 metres, McDonough superbly split the uprights to ultimately propel his side into the penultimate rounds.
Scorers for Castleknock College: B Griffin 2 tries, L McDonough pen, con.
Scorers for Belvedere College: Peter O’Farrell, J Sargent try each, J Tormey 2 cons.
CASTLEKNOCK COLLEGE: C Delaney; A Watson, F Gibbons, C Dunne, J Rooney; L McDonough, C Deegan; B Bislin, A Creedon, B Griffin; L Callinan, S Callinan; F Stanley, C McCarrick, I Birmingham.
Replacements: W Hennessy for Dunne (38), E Keogh for Birmingham (62), C Mahon for Deegan (63), G Quinn for Bislin, J Duffy for L Callinan (65).
BELVEDERE COLLEGE: D Hawkshaw; J Dillon, Peter O’Farrell, J Tormey, E Mac Adaimh; F McCarrick, J MacNiece; J Sargent, C Marrey, H Flood; E Murphy, D Coan; J Ross, Z Hayden, H McPeake.
Replacements: D O’Driscoll for Hayden (h-t), B McCabe for McPeake, W Finegan for Mac Adaimh (both 47), Patrick O’Farrell for MacNiece, J Maher for Dillon (both 68).
Referee: M Casey (LRR).