The New Zealand sharp-shooter was on the end of a terrific cross from Jason Culina to head past Clint Bolton on 36 minutes and give Miron Bleiberg's men a big lift after a turbulent period.

Sydney's defence struggled with the speed and touch of the home side, and their job was made so much more difficult after losing midfield general and captain Steve Corica with a leg injury after just 18 minutes.

After a week of criticism, Jason Culina was sharp in the centre of the pitch, his combinations with Zenon Caravella and Steve Pantelidis will surely give coach Miron Bleiberg a foundation to build on heading into the back end of the season.

Both teams started the match cautiously with neither prepared to show their hand too early in the contest, but it was the visitors who gave the first scare when their front-men had their best chance of the night.

A deft touch from Bridge allowed Brosque some space at the top of the box but Scott Higgins was on the spot to deny the shot.

As the match went on the home side grabbed the ascendancy and came with a flurry of attacking opportunities midway through the first half.

When Seb Ryall fouled Caravella, Culina was given a dead-ball chance from the sideline. Culina curled the ball into the box and landed it right at the feet of Smeltz but Sydney keeper Clint Bolton got a toe to the ball and knocked it safely behind goal.

Culina stepped up again to take the corner and after a scrimmage in the box Caravella blasted away from 20 metres but was well off target with the shot.

Gold Coast continued to pile on the pressure and when Fitzimmons put a neat chip in from the wing Smeltz had a golden opportunity only for his header to stray past the upright.

But Sydney's relief was fleeting as Culina came pouring down the flank and delivered an almost identical cross for Smeltz to put the Coast up 1-0 with a deft header past Bolton and into the top left corner.

Moments later United were at it again down the same corridor, this time Porter found Caravella with a nice ball, but with plenty of net to shoot for Caravella could only manage to guide the ball into Bolton's left leg.

With Culina seeing plenty of ball, rugged Sydney midfielder Stuart Musialik attempted to manhandle the United skipper but Culina was having none of it and both men were shown yellow cards as a scuffle erupted.