The Caltex Socceroos have lost their place in the world's top 50 nations following the release of the latest FIFA rankings on Thursday.
Ange Postecoglou's squad have slipped nine places to no.59 as a result of last week's 2-1 loss to England (11th) at the Stadium of Light.
It was the first time the squad had played together since winning through to the final phase of AFC qualifying for the next FIFA World Cup, which will kick-off in September.
Australia will play Iraq (102nd), United Arab Emirates (70th), Saudi Arabia (65th) and Japan (53rd), with the top two teams booking themselves a place at Russia 2018.
The Socceroos will have the chance to surge back up the rankings when they play Greece (40th) in Sydney on Saturday night and Melbourne on Tuesday night.
Argentina and Belgium retained their places as the top two nations in the world, while Colombia jumped into third.