The Reds were forced to play with 10 men after Fabian Barbiero was given a red card in the seventh minute for dragging Mark Bridge down as the Sky Blue's player streamed towards an open goal.

But the setback had no impact on United's hunger, with the home side taking a 2-0 lead thanks to striker Cristiano.

The Brazilian was paired with youngster Mathew Leckie up front, in favour of Lloyd Owusu, and the extravert didn't disappoint.

He struck in 29th and 54th minutes to earn his team a valuable three points.

Sydney never gave up and pegged one back through substitute striker John Aloisi.

The Sky Blues attacked to the end but didn't have enough of their key players at the top of their game to claim an away win.

Adelaide's first goal came from a copybook set-play. Cristiano worked his way through traffic before leaping and heading home a Scott Jamieson corner kick, his shot passing goalkeeper Clinton Bolton's right armpit.

The same players combined again to extend United's lead in the second half with Cristiano nodding the left back's long free kick across the goal line. A diving Bolton got to the ball on this occasion but couldn't control the slippery ball.

Cristiano was thrilled with his efforts and went to the fence to celebrate with supporters.

Sydney was in deep trouble and the introduction of Aloisi after about an hour of play was an inspired move.

At the 78th minute Eugene Galekovic made a terrific save to deflect a Terry McFlynn strike but couldn't recover in time to stop Aloisi swooping on a loose ball from close range.

The Reds knew they had a hard night ahead when Barbiero was sent off the pitch.

But the sacrificial act had a short-term benefit as the resultant Steve Corica free kick, close to the 'D', cannoned into the United defensive wall.

It didn't harm the home side's morale either with the Reds matching the Sky Blues intensity in the opening 45 minutes.

The dual striker set-up was working well with Cristiano's clean possession bringing other players into the mix while Leckie's pace and footwork had the Sky Blues defenders under the pump.

While Adelaide were working hard, it couldn't stop Sydney attacking the goals on a regular basis. Stuart Musialik and Simon Colosimo were off target with their 22nd-minute attempts while Shannon Cole's long, low shot on the half was covered by goalkeeper Galekovic.

Sydney's best chance came at the 41st minute when Alex Brosque streamed towards goal with Mark Rudan on his tail. Most would back Brosque to beat Rudan in a foot race every day of the week but the Reds defender hung in there and got a foot to the ball just as the striker was about to pull the trigger.

Rudan denied Brosque another scoring opportunity when he smothered a close range attempt in the opening minute of the second half. It provided only temporarily relief for the Reds with the visitors pressing hard for equaliser.

And it almost came in the 50th minute when a Karol Kisel header went cannoning into the right-hand goal post.

Their close call was quickly forgotten however when Cristiano struck for the second time.

With the situation dire, Sydney coach Vitezslav Lavicka brought Aloisi on for Cole. It aided the visitors' attacking approach and after some rushed and inaccurate forays into attack the veteran struck.

It was a nail-biting finish, with both sides' intensity giving the goalkeepers heart palpitations, but the home side held on.