Cassio, who three weeks ago was disgruntled about his position in the team, was all smiles after gaining the ultimate result from a damaging free kick in the 33rd minute of his comeback game.

The Brazilian cleared the Mariners' defensive wall, goalkeeper Danny Vukovic's outstretched hand before getting a favourable rebound off the crossbar to score.

It was a breakthrough result for the Reds who hadn't won since Round 1 and have struggled in the past month to field their best side.

United now have eight points from their six games and are sure to make a dramatic move up the competition ladder by the weekend's end.

It was Central Coast's second loss for the season.

Adelaide dominated the first half with their players returning from injury and Lloyd Owusu, who nursed a sore neck in the build-up to the game, the key contributors.

Travis Dodd added zip and enthusiasm to the midfield but his finishing was rusty after two weeks on the sidelines with a calf injury.

He had a fresh air shot in the opening minute of the contest, lacked penetration with a header in the third minute and was among a group of United players who couldn't push a ball over the goal line from point-blank range in the 11th.

Owusu and Cassio, who has missed games with a calf injury, also found space and missed opportunities to put their side in front.

But overall the home side would've been pleased with their efforts and time in attack.

Central Coast would've gone into the break with some optimism despite trailing the Reds.

A Matt Simon header in the eighth minute was cleared on the goal line by Alemao while Ahmad Elrich's curling strike at the 36th caused some concern for Galekovic.

Elrich was replaced by Dean Heffernan in the second half and the Mariners went about finding an equaliser.

They had a couple of early corners and Alex Wilkinson was gaining plenty of possession deep in attack.

But when the equaliser didn't come the contest became a little ragged with some sloppy tackles and some frustrated body language filtering into both team's approach.

The Mariners were fairing worst from the dogfight with John Hutchison and Matt Simon receiving yellow cards and coach Lawrie McKinna trying his luck with another two substitutes.

Central Coast pressed until the final whistle blew but a tired and brave Reds defence, led by Mark Rudan and Michael Marrone, ensured their side would be collecting maximum points.