Adelaide United young gun Luka Jovanovic has scored in the 92nd minute to fire his side to an A-League Men 2-1 win and snap Macarthur FC's six-game undefeated run.

After being dropped by Carl Veart last round for disciplinary reasons, Jovanovic announced his return by gifting the Reds the three points with a superb volley at Campbelltown Stadium on Sunday.

Valere Germain had broken the stalemate in the 80th minute with a sublime header to put the Bulls in pole position, but a reckless challenge by Oliver Randazzo just two minutes later opened the door for the Reds.

The 18-year-old defender Randazzo attempted to shepherd Yaya Dukuly but instead tripped his opponent in the box.

After missing a number of chances in the first half, Zach Clough stood up to take the penalty and easily converted.

Jovanovic then toe-poked the ball home after another foul on Dukuly gave the Reds a free kick.

The 19-year-old had been dropped by Veart in their last meeting with Western Sydney after expressing his frustration as an unused substitute in their round 9 draw with Sydney FC.

Adelaide went on to lose 3-2 to the Wanderers, suffering their first defeat of the season.

"Not just Luka, all our young boys, they're going to make mistakes," Veart said.

"It's important that they learn from them and they just keep working hard, because when you work hard, you get results.

"Luka, when he came on tonight, he worked hard. He was chasing and putting them under pressure."

Adelaide returned to second on the table on 21 points with their first away win at Campbelltown Stadium, while the Bulls drop to fifth (18 points).

"We had a little setback tonight, but hopefully it's the wake-up call that we need," Bulls coach Mile Sterjovski said.

"We want to fight for top position. We wouldn't be playing this game if we didn't want to win.

"Our squad is capable of winning the league."

The visitors were the more daring and creative side in the opening half but were wasteful when it mattered.

Clough was left lamenting a missed opportunity after his attempt from point-blank range in the 12th minute hit the post.

Rubbing more salt into the wound, Stefan Mauk's goal in the 17th minute was chalked off after Clough was found to be offside in the lead-up.

Macarthur turned in an uncharacteristically lacklustre performance, making eight shots at goal to 14 - none of which were on target.

Luke Brattan sent the ball straight into the Reds' wall in the 27th minute after earning a free kick when Jay Barnett fouled his Bulls teammate Marin Jakolis.

Brattan then sent a scare through the Macarthur camp after his left knee gave way eight minutes later.

The defensive midfielder had been caught in the ground after he began to sprint after Ethan Alagich, but shook off the complaint to see out the match.