Fresh off a spirited display in a 3-1 defeat to Chile in their FIFA World Cup Group B opener, Australia once more impressed in an exhilarating contest against Louis van Gaal's men, and even led 2-1 before eventually succumbing to a 3-2 defeat in Porto Alegre on Wednesday.
Arjen Robben sparked the game into life with a drilled finish in the 20th minute, but just a minute later Tim Cahill levelled with an astonishing first-time volley.
Things got even better for Australia when Mile Jedinak kept his cool to score from the penalty spot after Daryl Janmaat was somewhat harshly ruled to have handballed in the area.
However, the Netherlands rallied and Robin van Persie joined Robben in scoring three goals in the tournament, before substitute Memphis Depay tried his luck from distance, and ended Australian hopes.
Postecoglou felt his side deserved more for their efforts, but is confident that his charges will not be taken lightly in the future.
"We were playing against three of the best nations in the world," he said. "People said we weren't going to even score a goal.
"The goal was to (perform, so that) when we come back in four years' time, they fear us before the game and not just when they see us on the pitch.
"I put pressure on the players and the staff to go and get at the big teams. Saying it and doing it two different things. But today they did that and they didn't get a reward. It's heartbreaking.
"The players deserved a reward today. Everyone was outstanding. For the majority of the game, we looked more likely to win than game than not."
Postecoglou must now have to energise his side for their final Group B clash with reigning champions Spain, but he will have to plan without Cahill who will be suspended after picking up his second caution of the tournament.
Speaking to television reporters, he added: "Timmy was magnificent again and he led from the front.
"We haven't made one excuse all the way through about players being missing. Today we went out their and said we'd have a go. We did and we'll do it in the last game.
"Timmy will miss out but somebody will get an opportunity and they'll show the same endeavour that the other lads have shown."
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