Sydney FC remain in the title hunt after an uninspired win over Adelaide United but it is their cross city rivals who end 2019 as shock leaders.
W-League champions Sydney FC were forced to rely on an own goal and a spectacular last-minute Princess Ibini strike to earn a scratchy 2-0 win over an unlucky Adelaide United on Sunday.
The win retains the Sky Blues' hold on third but it is rivals Western Sydney Wanderers who unexpectedly end the year at the top of the standings, clear of Melbourne City on goal difference.
Sydney FC's title-winning form of last season seemed a distant memory as they struggled to overcome the winless Adelaide at Kogarah Jubilee Oval.
Goalscoring opportunities were few and far between, with Adelaide's in-form goalkeeper Sarah Willacy looking unbeatable on the few occasions she was called into action.
Chloe Logarzo failed to convert a gilt-edged chance for Sydney while Adelaide's Mallory Weber did likewise at the other end.
The deadlock remained until 14 minutes from the end when Remy Siemsen's cross was turned into the net by covering defender Amber Brooks.
Ibini ended the contest in the final minute with a sweet 20 metre strike, with the win leaving the Sky Blues a point shy of the summit.
Western Sydney Wanderers took full advantage of Melbourne City's week off by opening the round with another blistering win, this time 4-0 over Canberra United on Thursday.
The Wanderers, who have never featured in the semi-finals, ran rampant in the second half to back up last week's 5-0 win over Sydney FC in style.
Youngster Hollie Palmer scored a second-half winner as Brisbane Roar picked up an action-packed 2-1 win over Newcastle Jets to leapfrog Canberra into fourth.
The match marked the first outing for Matildas stalwart Elise Kellond-Knight who came on in the second half for Brisbane after missing the first half of the season.
Last season's table-toppers Melbourne Victory stayed in touch with the top-four thanks to an unlikely double from Amy Jackson for a 2-1 result over the winless Perth Glory.
The veteran midfielder's brace included a strong contender for goal of the year with her second-half long-range winner crashing home off the underside of the crossbar.
At the other end, former Matildas goalkeeper Casey Dumont made a third penalty save of the season, denying Crystal Thomas from the spot to ensure the visitors took all three points home.