Considered rank outsiders to progress to the second round, Australia were within touching distance of the feat in Moscow overnight, Australian time.
The Socceroos led 1-0 against South American champions Chile and spurned a number of golden chances to increase their lead.
The world No.4 side hit back, scrambling a goal home to earn a share of the spoils and progress to the next phase.
The Socceroos leave Russia after finishing third in their group, losing 3-2 to Germany and drawing 1-1 with both Cameroon and Chile.
Postecoglou credited his players for their effort but couldn’t shake the feeling it could have been very different.
“It’s definitely a missed opportunity. We wanted to come here and at least get out of the group and we haven’t,” Postecoglou said.
“If you look at the context of the three games we were in every game (so I’m) disappointed that we couldn’t get through.
“That’s me setting the highest possible benchmarks which I think we have to if we want to consistently compete at this level.
“For the boys to do that tonight, I think they’ll get a great amount of belief out of it.”
The Socceroos saved their best performance of the tournament for last.
Led by Tim Cahill in his 100th game, Australia played with confidence and dare against a side 44 places above them in the FIFA rankings – and that beat the Socceroos 3-1 at the last World Cup.
Mark Milligan kept Arsenal star Alexis Sanchez at bay.
Jackson Irvine and Massimo Luongo were composed and sharp in the middle.
Trent Sainsbury was a tower at the back and James Troisi took his chance well.
And most impressively, the entire side executed the game plan for the entire 90 minutes.
“We played them four years ago and we thought we gave them a good game that day but they were just a little bit better than us,” Postecoglou said.
“Today I thought we were the better side and deserved to get something out of it. ”
The Socceroos coach made six changes for the do-or-die Confederations Cup clash – and even by Postecoglou’s funky selection standards, it was a shake-up for the ages.
Team stalwarts were thrown around.
Milligan was moved to centre back, Cahill was put in attacking midfield for his 100th match and Robbie Kruse was asked to do his share of defending in the advanced right wing role.
A new pairing – Massimo Luongo and Jackson Irvine – were deployed as holding midfielders.
In doing so, first team regulars Aaron Mooy, Tom Rogic and Mathew Leckie were denied the chance to take on Chile; one of the biggest occasions of their international career.
Was this really the match to throw in such an experimental lineup?
Cahill led from the front in the 1-1 draw. Milligan shut down Alexis Sanchez. Irvine was a revelation.
Luongo bounced back from his shocker against Germany and Kruse fired Australia forward time and again.
Not for the first time in his tenure, Postecoglou was questioned and was vindicated.
“We had guys waiting that didn’t play in the first two games that we knew would bring energy to the group and maintain our style of football,” Postecoglou said.
“We were going to need it today because they’re a world class team. Credit to the guys who came in. They certainly brought energy.”
Postecoglou paid tribute to players that came in and played beyond their capacity given lay-offs.
“We’re asking these guys to the most ridiculous things but we’re trying to set our standards high,” he said.
“Trent Sainsbury has played 20 minutes of football all year.
“Guys like Millsy, James Troisi, his last club game was early May.
“The kind of game we wanted to play needs a lot of energy and high levels of fitness.
“We didn’t have that coming into this tournament because of the nature of where our players at at the moment.
“That’s something we need to rectify. The fact that they just kept going speaks volumes.”
Milligan’s best moment was a last gasp tackle on Sanchez which prevented a near-certain goal.
“He is world class. He escaped my clutches a few times,” Milligan said, smiling.
The 31-year-old said he hoped the performance convinced a few doubters.
“Hopefully everyone now can see what we’re trying to achieve and the direction we’re trying to head in. It’s been a worthwhile trip,” he said.
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