City have won all six of their opening games and the shackles came off against Roar as they scored all four goals in the second half.
City were in control of the contest from the outset despite missing their most influential players Lisa De Vanna (suspension) and Jess Fishlock (international duty for Wales).
Brisbane's American goalkeeper Haley Kopmeyer also kept her side in contention with a string of good saves.
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However. the visitors started to feel the pressure as Ruth Blackburn was a awarded a straight red card after 49 minutes.
Within a matter of minutes City found the opener as Kim Little finished off a well worked move orchestrated by Marianna Tabian.
Little made it 2-0 as she rounded the keeper expertly before the in-form Larissa Crummer scored two in two minutes.
Crummer took her tally to eight goals in six games as she scored on the 78th minute and 80th minute with a superb long-range strike.
Adelaide United and Newcastle Jets drew 1-1 as the home side remain second on the ladder.
Tiarn Powell gave the Lady Reds the lead but Tara Andrews ensured that jets returned home with a share of the spoils. Full highlights can be found in the video.
In the fnial game, Canberra United snatched a late winner to overcome Sydney FC 1-0.
Sydney had marginally the better of a tight contest at home, with striker Jasmyne Spencer coming close on several occasions.
But Nicole Begg was the hero as she found the net in the 88th minute after an incredibly tight encouner.
