Melbourne Victory closed the gap to A-League leaders Sydney with a 2-0 win away to Adelaide United on Saturday.
Kevin Muscat's side triumphed over their fierce rivals thanks to a goal in each half from James Troisi and Besart Berisha, inflicting a ninth defeat in 14 matches for the reigning champions.
Sergi Guardiola came close for the home side before Troisi fired in from Berisha's pass to put Victory ahead after 22 minutes at Coopers Stadium.
United had twice the number of shots as Victory but lacked a cutting edge and they were punished 22 minutes from time, when Troisi turned provider for Berisha to nod the ball into the bottom corner.
The result puts Victory back to within four points of Sydney, while United stay bottom on seven.
Newcastle Jets edged closer to fourth-placed Brisbane Roar after a thrilling 3-2 victory over John Aloisi's side at Suncorp Stadium in the earlier match.
Tommy Oar drilled home from outside the box to put Roar ahead before Andrew Hoole coolly fired in the equaliser just before half-time.
Andrew Nabbout headed the Jets ahead midway through the second half but the home side drew level when Jamie Maclaren converted from the spot after a clumsy foul from Nigel Boogaard on Jack Hingert.
However, within two minutes remaining, the Jets struck the winning goal, with Morten Nordstrand converting from close range to seal the win that moves them to within five points of Roar and just one behind fifth-place Perth Glory.