They were denied a goal by a controversial offside decision from a linesman, but so clinical were Sydney that they rendered that call moot as goals to Alex Brosque and Milos Ninkovic in the second half sealed their 12th win of the season.

Yet again, they were ruthless in an attack, fluent in possession and quick in transition - but most impressively, impenetrable in defence. A backline that will only become stronger with the addition of new Dutch signing Jordy Buijs who's awaiting his international transfer clearance looked insurmountable, holding on for their tenth clean sheet in 16 games. According to their coach Graham Arnold, their intuition was so strong that his half-time message during the break was play on instinct.

"They looked like they were thinking too much, just do what comes natural. Just have a go and finish the opportunities off. I thought it was a much improved performance with the ball," Arnold said.

It ensured the Sky Blues enter Thursday's Big Blue against second-placed Melbourne Victory with an air of confidence and the knowledge that the minor premiership could become all-but sealed by round 17 with a win at Etihad Stadium.

If Sydney were guilty of being timid at times in last week's derby then they immediately quashed any suggestions that that display would become the norm.

Relentless waves of attack sliced through Adelaide's defence with ease, putting last season's "tiki-taka" champions in an unfamiliar and uncomfortable position of chasing shadows.

Sydney were happy playing pretty but for all their possession, they struggled to make their dominance count in the early stanzas and and were lucky not to have gone a man down after 16 minutes. A shocking tackle by Rhyan Grant should have ended his night prematurely and could have ended Marcelo Carrusca's season. Sydney's full back went flying in on Adelaide's playmaker with two feet off the ground and crashed studs first into Carrusca's ankle, but in a baffling decision referee Shaun Evans only showed a yellow.

That call kept Grant on the field for the remainder of the match, though his fifth caution still meant he was suspended for next week's top-of-the-table clash with Melbourne Victory.

The officiating nightmares didn't stop there and Adelaide were paid some sense of justice with a fortuitous call from the linesman. Filip Holosko was played through on goal by Ninkovic and slotted the ball calmly past Eugene Galekovic in goals before being flagged for offside. Replays suggested the Slovakian was narrowly on. 

Another one: Alex Brosque's sharp finish opened the scoring. Photo: Getty Images

Sydney goalkeeper Danny Vukovic continued his protests down the tunnel into the break, re-emerging for the second half to be greeted with a caution from Evans for dissent.

Frustrated, they may have been but the Sky Blues were determined to make that decision was irrelevant by the final whistle and Brosque immediately tested Galekovic from close range. Ninkovic attempted to curl a volley into the corner of the net minutes later before Sydney's captain finally unravelled the Reds' backline.

If Adelaide weren't already cursing the lenient decision to keep Grant on the field then Sydney's fullback left them red-faced with an inch-perfect deep cross to find Brosque in his stride. Showing all his experience and awareness, Brosque struck placed volley into the corner of the net to break the deadlock.

Sydney's fans were still celebrating when they made it two in style. There are few greater traits of a superb talent than finding space when there is seemingly none and Ninkovic did just that, opening room to shoot inside a packed box. Two touches gave him breathing space and a third curled the ball into the corner of the net to give the hosts a commanding lead in the contest and at the top of the competition.