Paraguay looms as the sternest test on Australia's journey from June's World Cup to January's Asian Cup.
After acquitting themselves well under new boss Holger Osieck in Switzerland and Poland, the Socceroos are up against their highest-ranked opposition since appearing on the big stage in South Africa.
It took eventual champions Spain to knock out the 17th-ranked Paraguay in the World Cup quarter finals, thanks to a late penalty.
Only David Villa's spot kick separated them.
Like all top teams, Paraguay give nothing away at the back and are lethal on the break with speed, deft touch and precise long balls.
They will test Australia at both ends of the Sydney Football Stadium.
Australia's relatively inexperienced centreback pairing - no matter which two out of Jon McKain, Michael Thwaite and Jade North are picked - is sure to come under pressure.
Up front, meanwhile, the Socceroos strikers - possibly Josh Kennedy and Scott McDonald - will be trying to crack a defence which conceded just two goals in five matches at the World Cup.
In their group matches Paraguay drew 1-1 with defending champions Italy, beat Slovakia 2-0 then ended up all square and goalless against brave New Zealand.
The South Americans had another goalless draw against Japan in the round of 16 before winning 5-3 on penalties, then bowed out to Spain at the next hurdle.
Without question Australia's biggest threat will come from Nelson Valdez, scorer of one of those penalties, who enjoyed immediate success at club level in Spain this year after starring in Germany's Bundesliga for almost a decade.
After switching from Borussia Dortmund to Spanish club Hercules, Valdez stunned mighty Barcelona by scoring both goals in his team's 2-0 victory at the Nou Camp.
The Socceroos can be thankful that three of Paraguay's stars have not made the trip to Australia - Oscar Cardozo, Lucas Barrios and Manchester City's Roque Santa Cruz.
Midfielder Nestor Ortigoza is also absent.
But Paraguay will still represent formidable opposition, even coming off two modest results on a tour of east Asia last month - a 1-1 draw with China and a 1-0 loss to Japan.
"Paraguay showed at the World Cup how strong they are," said Australian goalkeeper and captain Mark Schwarzer.
"Our boys will be raring to go.
"There's always a great deal of motivation to play against a highly ranked team.
"It would be nice for confidence and team morale to get a result against them.