Melbourne City leapfrogged Sydney FC to the A-League Women Premier's Plate on Sunday after wildly contrasting results on opposite coasts of Australia.

At Leichhardt Oval, Melbourne Victory spoiled Sydney's party with a stunning 4-0 result capped by a shocking blunder by goalkeeper Jada Whyman.

Three hours later in Perth, City capitalised on their slip-up, winning 2-1 and surviving a late scare from Perth Glory to claim the premiership.

Rhianna Pollicina put the visitors ahead with one of the goals of the season.

Receiving the ball with her back to goal, Pollicina turned her marker and fired a curling shot to the back post, beating Morgan Aquino at full stretch.

Leading from the eighth minute, City held Glory at arm's length for the contest before Shelby McMahon — the Young Matildas captain — made a late entrance and sealed the result.

The 15-year-old picked the perfect time to score her first senior goal, receiving the ball from the by-line and dancing between two Glory defenders before blasting home at the near post.

While Perth's Tanika Lala lashed a 94th minute goal to spark concern, Dario Vidosic's side held on to celebrate in the West.

Sydney FC, who started the week knowing wins over Canberra or Melbourne Victory would seal a fourth-straight premiership, instead blew both shots at silverware.

After a 1-0 defeat in the capital on Wednesday, the Sky Blues were off colour again on Sunday and weren't helped by Whyman's moment of madness.

Already trailing to Alana Murphy's close range volley, the Matildas goalkeeper was in possession but clearly ankle-tapped fellow international Alex Chidiac, producing a yellow card and penalty, dispatched by former teammate Rachel Lowe.

Emily Gielnik scored a superb third just after the hour and Chidiac added the exclamation point, racing clear in injury time and finishing coolly for the 4-0 win.

The result saved Victory's season. They started the day outside the top six but jumped to fourth on a log-jammed table.

Squeezed out of the finals was Western Sydney, who miss out on just their second post-season outing in 12 seasons.

Victory's win also means the first week of the finals — after a week off for international matches — will take place in Melbourne.

Third-placed Western will host Newcastle Jets, while Victory's prize for jumping to fourth is a home final against Central Coast.

Top two City and Sydney FC enjoyed contrasting Sundays but will enjoy a fortnight off to either celebrate or commiserate before entering the finals in the last four.

AAP