He found out on Tuesday night in Melbourne just how good the best can be when his Socceroo side tried determinedly but was distinctly second best against a Brazilian team anxious to make up for his 1-0 loss to Argentina at the MCG last Friday night.

The final scoreline showed Brazil were 4-0 winners, but in reality it could have been more had the South Americans taken all of the chances that fell their way.

The Socceroos still have a long way to go if they want to mix it at the top table of the world game, which is Postecoglou's declared ambition. They can take some comfort from the fact they will face few opponents as good as Brazil.

It didn't help Australia's cause that it was fighting an uphill battle after just 12 seconds following a calamitous opening that saw the Brazilians take the lead through Diego Souza.

There has been much debate about the efficacy of Postecoglou's decision to play with a back three, and plenty of criticism – some, if not all of it, justified – for the way the team has adapted to its new tactical structure in recent matches.

But Brazil's opener had nothing to do with team shape or set up. Australia could have had a back seven but still conceded after Bailey Wright's howler which gifted possession to Giuliano straight from the kick-off.

The midfielder slid the ball through to Souza, who fired past Mitchell Langerak after the goalkeeper got a wrist to the ball.

To their credit Australia dug in, weathered an early storm and managed to keep their opponents scoreless through the rest of the first half.

Despite wholesale changes – only Thiago Silva, Phillipe Coutinho and Paulinho started in the loss to Argentina – Brazil looked smooth and in perfect rhythm with Coutinho, in particular, looking unplayable at times as he slipped past opponents and glided in the lines between midfield and attack, dribbling round defenders or sliding passes through to teammates.

Even though they were often chasing shadows Australia stuck to their task and created a handful of openings of their own.

The best of those came after a quarter of an hour when James Troisi – one of five current or former Melbourne Victory players in the starting line-up for Australia – fed another ex-Victory man in Aziz Behich down the left. The latter's cross would surely have found captain for the night Tim Cahill had not Rodrigo Russo got back in time to deflect the ball wide for a corner.

Brazil retained possession with ease and were quicker to the ball, quick to intercept, and quick to put pressure on Australia whenever the yellow shirts looked to get forward.

The visitors did have the ball in the net a second time just on the half hour when David Luiz stepped in to intercept a pass out of defence before playing Souza in. The forward chipped the ball past Langerak but was clearly offside.

Paulinho could have made it two goals three minutes later after a withering attack down the left by Alex Sandro found Souza, whose cheeky back heel put the ball right on the former Tottenham man's toe. Much to Australia's relief he chipped the ball over the bar.

This was a match that Postecoglou was using to play his team into form and ensure that all members of his squad were match fit and sharp for Russia, so he too made wholesale changes, with debutant Ajdin Hrustic getting a start off the bench he could scarcely have dreamed of a few weeks ago.

Brazil doubled their advantage around the hour mark and it was a goal from a corner that sealed the game.

Coutinho's outswinging kick was met with a perfectly timed run and powerful header from Luiz, whose effort came back off the crossbar. Australia could not clear and in the ensuing scramble veteran defender Thiago Silva reacted best to head in the bouncing ball.

Langerak made a couple of good reaction saves to prevent the lead extending, but he could do nothing to prevent Taison scoring after some terrific interplay between Chelsea star Willian and Paulinho carved open Australia's defence. Souza made it four with a goal in the dying seconds, but it was academic by then.

It doesn't get much easier for the Socceroos, as they face Germany in their opening Confederations Cup game in five days time.

After the match, Postecoglou said he took the blame for the scoreline after making a number of second-half substitutions.

"I will take responsibility for that in the second half, we were very disjointed, we conceded from set pieces. You always learn from every game, it was important for players to get minutes," he said.