Roar dominated possession in the first-half but it was mostly in their own half with United pressing hard, although Erik Paartalu's 15th-minute goal eased the tension for the hosts.

Eventually Gold Coast tired and further strikes came thanks to Besart Berisha and Mitch Nichols following the introduction of Kofi Danning and Massimo Murdocca – who provided the assist for the Albanian's goal.

However, Postecoglou told Fox Sports after the game he wasn't happy with the performance.

“You need to look at tonight in isolation and we weren't great tonight,” Postecoglou said.

“We started off a bit slow, didn't get any rhythm in the game. The effort was there, we worked hard and broke their spirit a bit.

“In terms of the kind of football we want to play it wasn't our best night.”

On substitutes Murdocca and Danning, Postecoglou added: “Mass was fantastic. Mass and Kofi when they came on. It's been hard leaving Mass out as he's been on fire at training and it's a matter of time before he breaks his way in there.

“He was fantastic tonight. He gave us a little bit of energy. He's clever and knocked some nice balls through. He made a massive impact on the game.”

Roar have maximum points from their opening three matches but Postecoglou insisted they need to improve.

“In the end it was a comfortable scoreline but in terms of the performance we can play a lot better,” he said.

“We have to improve. The rest of the competition will be better, so we have to be better than that. Weve' got some high standards we want to maintain and that didn't meet it tonight.”

Defeated United coach Miron Bleiberg said the scoreline was harsh considering his side's efforts.

“1-0 or 3-0 is the same. It feels harsh, but it's the luck of the chamions that they can squeeze the result in their favour,” he said.

Former Netherlands youth international and Blackburn striker Maceo Rigters was a bright point for United after an impressive debut.

“I warned everybody that we are talking about somebody who is a good striker,” Bleiberg said.

“He's strong, he's quick, he's a good footballer, he's dangerous and he's hungry. He still needs to get match fitness but  most defences in the A-League will notice him.”