The Caltex Socceroos have fallen three spots to 40th in the latest FIFA rankings released on Thursday night (AEST).
The fall comes after a bag of mixed results in friendlies against Norway and Colombia, which Australia lost 4-1 and drew 0-0 respectively.
Iran remains the highest ranked Asian side in 36th spot, dropping three spots from March.
France, Australia's first opponent at the World Cup in Russia, have jumped two places to sixth in the rankings.
There was no movement for Peru, in 11th, or Denmark in 12th.
Upcoming friendly opponents Czech Republic have fallen two spots to 45th, while Hungary remain static in 50th.