Western United will play off for a spot in the A-League Grand Final, after defeating Brisbane Roar 1-0 at Bankwest Stadium on Sunday night.
A stunning free-kick by Alessandro Diamanti was enough to split the two sides in the Elimination Final.
The United captain's curling effort from range rebounded off the post before crossing the line to give the Green and Black the lead.
There were chances aplenty for both sides in the the second half.
Brad Inman's strike rattled off the post for Brisbane, while Besart Berisha and Steven Lustica missed chances for United at the other end.
But a solid defensive effort from Mark Rudan's side ensured they held on for another historic win.
The Green and Black progress through to the A-League semi-finals - a notable achievement in their inaugural season.
Western United will face Melbourne City on Wednesday, August 26 at Bankwest Stadium for a spot in the A-League Grand Final.
Brisbane Roar 0
Western United 1 (Diamanti 21')
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