Roar coach Frank Farina opted for inexperience and started debutant Calum O'Connell and second-gamer Ivan Franjic in defence, but it was old heads Josh McCloughan, Bob Malcolm and most notably keeper Liam Reddy that produced costly errors.

The vocal crowd of 7,367 was stunned into silence after just 45 seconds when a wayward header from McCloughan saw a cross from Mile Sterjovski end up in the back of the net for an own goal.

The visitors then doubled their lead on the eve of halftime when Wayne Srhoj pounced on an errant pass from Bob Malcolm and fired calmly past Reddy - who was all at sea after charging far out of his box.

The Roar, who created a handful of chances in the first half, continued to press and Brazilian flyer Henrique opened his side's account in the 50th minute - dancing past Glory defender Andy Todd and beating keeper Aleks Vrteski with a scorching shot.

Glory striker Branko Jelic and Roar counterpart Sergio van Dijjk then snaffled a goal apiece to set up a grandstand finish - the Glory holding a 3-2 advantage with 26 minutes left on the clock.

It was not to be though, Reddy coming up with his second remarkable blunder for the day to ensure all three points would head west.

Adriano Pellegrino whipped in a tame speculative cross that somehow slipped through the hands of an unobstructed Reddy and trickled into the back of the net.

Such was the nature of Reddy's fumble, there was discussion and debate over whether Pellegrino's 'strike' should be recorded as another own goal.

The win was Perth's first triumph away from Members Equity Stadium since 21 December 2008, and snapped a horror run that had seen them beaten by the Roar in 10 of the last 11 clashes between the two sides.

The Roar had a handful of opportunities throughout the fixture - Charlie Miller, van Dijk, Henrique and Reinaldo all looked lively - but ultimately were left to lament some schoolboy errors.

Aside from three of the goals coming after minimal effort from Perth, there were two instances in the opening half.

A mix-up between McCloughan and Reddy almost resulted in another own goal, while Franjic was called upon to make a sliding clearance off the line.