The Socceroos will end the year at No.41 in the latest FIFA world rankings.
As they prepare for a defence of their AFC Asian Cup crown next month, Graham Arnold's team will head into the tournament down three places on their ranking for the corresponding period in 2017.
It leaves Iran at 29th as the highest-placed side competing in the Asian Cup.
Host nation United Arab Emirates are 79th while Japan will go into the tournament at No.50 in the world.
The Socceroos will play the 109th-ranked Jordan in their opening Asian Cup Group B match at Hazza Bin Zayed Stadium on January 6.
Belgium end 2018 atop FIFA's rankings with 2018 FIFA World Cup winners France at No.2.
Belgium are a single ranking point - 1,727 to 1,726 - ahead of a France team who won their FIFA World Cup semi-final in Russia.
Brazil are No.3 and 2018 FIFA World Cup runner-up Croatia are No.4 in a mostly unchanged monthly ranking.
England and Portugal, who both qualified last month for the UEFA Nations League Final Four tournament, are No.5 and 6 respectively.
Uruguay, Switzerland, Spain, and Denmark complete the top 10, while Qatar, the 2022 FIFA World Cup host, are No. 93.