A point from substitute Tom O Suilleabhain, two minutes from time, saw Corn Ui Mhuiri holders Pobalscoil Chorca Dhuibhne escape to victory in atrocious conditions in Killarney.
The crucial score of the first half came in the fourth minute when Cathal O Bambaire finished Tomas O Se's high centre to the Rochestown net.
Aaron Ward and Alan O'Donovan with two points each and Mark Dolan were on the mark for the Cork side, while two frees from Seamus O Mhuircheartaigh were all Chorca Dhuibhne could muster as the sides retired level at the interval 1-2 to 0-5.
There wasn't a single score for the opening 18 minutes of the second half as both sides battled the elements before Rochestown hit the front with their only score of the second period through Dolan.
Within minutes Chorca Dhuibhne were level through Eanna O Conchuir's free and, with extra-time looming large, O Suilleabhain kicked a superb winner.
SCORERS – Pobalscoil Chorca Dhuibhne: C O Bambaire 1-0, S O Muircheartaigh 0-2f, E O Conchuir (f), T O Suilleabhain 0-1 each. Rochestown: A O'Donovan, A Ward (1f), M Dolan (1f) 0-2 each.
Pobalscoil Chorca Dhuibhne –D O Conchuir; B O Beaglaoich, C O Luing, C O Suilleabhain; M O Flatharta, P O Conchuir, M O Conchuir; B O Suilleabhain, C O Beaglaoich; T O Se, P Breathnach, P O Dubhain; S O Muircheartaigh, E O Conchuir, C O Bambaire. Subs: C O Muirthuile for C O Bambaire (h-t), T O Suilleabhainfor S O Muircheartaigh (40), M O Caomhanaigh for P Dubhain (45), R O Se for P Breathnach (55).
Rochestown – G Connolly; D Barrett, K Flahive, D Meaney; C Kingston, N Cashman, A Murphy; A O'Donovan, S O'Mahony; D O'Connor, K Hodgins, A Ward; M Dolan, C O'Brien, M O'Connor. Subs: C Cormack for C O'Brien (40, J Donovan for D O'Connor (53), L Carroll for A Ward (56)
Ref – M Meade (Limerick)