Cistercian, Roscrea, surrendered an early lead before bowing out at Athy yesterday.
They had first use of the wind and two penalties by Fergal Lawlor gave them an early lead.
However, fullback Ross McCarron ran from the halfway line for a try to open Gonzaga's account and they took the lead in the 20th minute when centre Graham King crossed for a try.
The elements favoured Gonzaga for the second half and a George Eves penalty made sure of victory.
Gonzaga: R McCarron; R O'Connor, G King, R Hickey, J McNicholas; G Eves, J Brady; N Morris, B Gahan, E McGrath, A Lee, M Kennedy, C Griffin, R O'Higgins, K McLaughlin.
Cistercian, Roscrea: M Garvey; B Walsh, D O'Meara, J Hughes, E Keely; F Lawlor, D Dineen; P Greene, J Egan, C Fitzgerald, B McIntyre, J O'Dwyer, J Byrne, B Hall, J Spencer. Replacements: D Joyce for Walsh, C Duignan for Dineen.
Referee: K Clayton (ARLB).