Monument and Waterkloof are expected to contest the final of the Beeld Trophy for bigger schools.
Last Saturday, defending champions Waterkloof beat Middelburg 39-23 in a pulsating fixture and will play Rustenburg, who beat Kempton Park 24-21, in the semi-finals.
Monument will meet EG Jansen from Boksburg in the other semi, after the latter defeated Centurion 16-13.
In the big schools section, Brits beat Riebeeckrand 24-11 to qualify for the semi-finals, and will face either Hans Merensky or Ermelo. The other semi will be between Klerksdorp and Transvalia. Klerksdorp ran out convincing 43-22 winners over Helpmekaar in their quarter-final clash, while Transvalia narrowly defeated Ben Vorster 20-18.
The medium schools semi-final line-up is Vryburg vs Piet Retief and Linden vs Volskrust, with Belfast vs Christiana and Heilbron vs Leeuwenhof the two small schools semi-finals.