A goal from Sergio van Dijk and a deflected own goal from Hayden Fox on the hour mark were enough for the Reds in the disappointing showpiece game in front of a 16, 429 crowd at Adelaide Oval.

The result was lacklustre Sydney's fifth straight loss, and fifth game without even scoring, anchoring them to the foot of the A-League ladder.

United had lost four of their past five matches but van Dijk's goal and Cassio's deflected cross were enough to return the Reds to the winners list.

Adelaide started promisingly as Argentine Marcos Flores set up Iain Ramsey with an early chance flicking a first-time through ball to the speedster.

Ramsey latched onto the pass and shot from eight metres but blasted straight into Liam Reddy with his non-preferred foot.

Sydney were restricted to shooting from distance and when they did manage to put one on target, Young Socceroo keeper Mark Birighitti had little trouble keeping the shot out.

Adelaide took the lead 10 minutes before half-time through their leading scorer Sergio van Dijk, who netted his 11th goal for the season to top Hyundai A-League goal scoring.

Van Dijk started the move in the middle, laying off to Paul Reid before the acting captain released Flores into space on the right.

The Argentine whipped in a cross and Sydney defender Stephan Keller managed to get a touch on ball, but his deflection allowed it to fall perfectly for van Dijk.

The Reds striker took a touch before smashing into the bottom corner from 10 metres.

Keller nearly redeemed himself and pulled his side level when he picked up a loose ball from a Scott Jamieson corner, shooting on the turn and struck the top of the bar in the closing minutes of the first half.

Sydney lifted in the second half as they went in search of an equaliser but again couldn't penetrate the United defence.

Shannon Cole tested Birighitti with a 25-metre free kick but the Reds shot stopper got down well to parry the shot to safety.

As the visitors committed men forward, United doubled their lead just before the hour after a marauding run from Cassio.

The little Brazilian raced on to a clever dink in behind the defence from Reid and charged down the left before his cross took a wicked deflection off Hayden Foxe and over Reddy and into the net.

Adelaide United 2 (van Dijk 35, Cassio 58)
Sydney FC 0
16, 429 at Adelaide Oval