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Tournament hosts Australia fell behind to Hussain Fadel's early goal in the Asian Cup opener in Melbourne.
However, the hosts had Luongo to thank for getting them back on track, the midfielder supplying the assist for Tim Cahill to level proceedings before heading his team in front a minute before the break.
From there Australia did not look back and they pulled clear in the second half of the Group A fixture courtesy of a Mile Jedinak penalty and James Troisi's late strike.
But it was the youngster making just his sixth appearance at full international level that earned his coach's praise after the game.
"Massimo Luongo was outstanding," Postecoglou said.
"He created the first goal, scored the second. But more importantly there was real urgency in what he did. I think he lifted a few around him because of that.
"He's one of the guys we've blooded in the last 14 months. He's one we've worked with, persevered with, put him in tough situations. He may be playing in the third tier of English football but his club form's been great.
"When he came into camp he was in great condition and looking good in training. He's a goal threat, whether it's creating goals or scoring goals."
It was almost inevitable that veteran forward Cahill would get on the scoresheet. The 35-year-old extended a remarkable record for his national team at major competitions, scoring at the last three World Cups and the last three Asian Cups, a run going back to Germany 2006.
"He's [Cahill] still a fantastic player, still very dangerous in the box," Postecoglou added.
"We saw that in the World Cup. Every time he's played for us, I think the way the team plays suits him as well. There wouldn't be a defender in the world today who'd like to be one-on-one with Tim Cahill, be that in the air or on the ground.
"We had multiple threats but Timmy's still very important to us."
Kuwait coach Nabil Maaloul conceded that his side were no match for Australia and were always up against it, despite taking the lead.
"Maybe I was the only one on the bench who did not express my happiness at the goal because I knew the strengths and weaknesses of our football team," he said.
"Also I knew the national team of Australia could come back at any point in the match and that happened.
"There was a big difference between the national team of Australia and national team of Kuwait, especially from the physical aspect."