The two sides went in level 1-1 at the break but a spot-kick from Craig Goodwin and one for the highlights reel from Ben Halloran steered the Reds to victory.
United coach Carl Veart was delighted with the Reds’ performance and recent run of form which has seen his side climb into second, one point behind league leader Central Coast.
“I think the boys again, the last seven eight weeks, the football that they’ve been playing and what I’ve been asking them to do, they’ve been doing it to a tee,” he said.
“I’m so happy for them and I’m so proud of them.”
Macarthur made a bright start but after the opening 10 minutes, the hosts began to assert their authority and broke the deadlock on 14 minutes.
Goodwin and Joe Calletti exchanged passes in a well-worked short corner with Goodwin whipping in a cross which Tomi Juric powerfully headed past Adam Federici.
Goodwin was again involved on the half hour, cutting in from the left and crossing to the far post with his right for Halloran to cushion a pass across the face of goal but there was no teammate for the tap in.
Two minutes later and Adelaide should have doubled their lead.
Ryan Strain split the Macarthur back three with a long ball out of defence, finding Juric in acres of space.
The striker had plenty of time to assess his options and attempted to lob Federici who was well off his line, but Juric’s effort was tame and easily collected by the visiting shot-stopper.
United were left to rue that chance and failing to capitalise on their dominance with Macarthur finding an equaliser against the run of play on 32 minutes.
Juric’s loose touch in the middle of the park was picked up by Jake Hollman who slipped in Matt Derbyshire with the English striker coolly curling his shot past Reds goalkeeper Joe Gauci.
United returned from the interval the better of the two sides and Goodwin almost found the net within the first couple of minutes.
Released by George Timotheou with a long ball from defence, Goodwin raced towards goal and fired a shot from a tight angle which forced Federici into a stunning reflex save.
Adelaide eventually got their second on 73 minutes and it was Goodwin involved again.
This time it was Elsey who launched a long ball from the defensive half for the Reds winger who latched onto the pass before being bowled over inside the area by Lachlan Rose.
Goodwin stepped up and coolly dispatched the spot-kick, sending Federici the wrong way.
Ten minutes later and Adelaide added a third courtesy of a stunner from Halloran.
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