Millfield, who had an edge at scrum time, reduced the deficit with a maul try in the second minute of the second half, and several times went close to levelling.
Meanwhile in a real arm-wrestle, Westlake were always trailing against Paul Roos Gymnasium, who were named School of the Year and Team of the Year in South Africa’s Ruggas Awards for 2024.
Paul Roos appeared to be without a number of stars from their unbeaten domestic season, but were still dominant and went ahead through an early penalty, a 23rd minute try and a further penalty to lead 11-0 at the break.
But with their first real attacking opportunity of the match early in the second half, Westlake were awarded a penalty try following two taps close to the Paul Roos line.
However Paul Roos closed the match out and Westlake will now face Millfield School in the playoff for third.
Meanwhile Papakura High School, competing in the second-tier Trophy division, have had a win and a loss so far in their campaign.
They beat RTA Barbarians, a South African Invitational XV, 21-20, but then lost 21-30 to Dess College, a private school in Dubai.