Perth SC will meet Perth RedStar in the final of the Hyundai Women's State Cup at the Sam Kerr Football Centre in September.
The Azzurri booked their spot on Tuesday with a 4-1 win over Fremantle City at a sodden Dorrien Gardens.
Ella Lincoln turned in the box to fire the hosts ahead before Annabelle Leek responded for Freo with an outstanding free-kick. Sam Mathers restored Perth's lead just before half-time when she took advantage of some hesitant defending, before Lincoln set up Epril Nossent for the third and Anika Stajcic added a fourth near the end.
On Wednesday, RedStar beat Balcatta Etna 3-0 at Home Group Stadium.
Three days on from winning there in the league, the NPLW leaders were ahead inside two minutes when Reina Kagami followed up after Katie Ritchie's shot had been saved.
Kagami was involved again 20 minutes from time when her cross was inadvertently put into her own net by Janelle St-Pierre. Manami Arai capped a fine night for RedStar in stoppage time by collecting Sarah Carroll's excellent through ball and rounding keeper Beck Bennett before scoring.