Japan booked their berth at next year's World Cup finals as Vahid Halilhodzic's side handed Australia a 2-0 defeat on Thursday evening that guarantees the Samurai Blue top spot in Group B of Asia's qualifying campaign for Russia 2018.

Takuma Asano gave the Japanese the lead four minutes before the half-time break when he was left unmarked to slide Yuto Nagatomo's cross beyond Mat Ryan to put Japan in front after Mathew Leckie had earlier hit the post for the Socceroos.

Eight minutes from time Yosuke Ideguchi put the result beyond doubt with a thunderous strike from outside the area that sent the sold out Saitama Stadium into a frenzy.

Victory moves Halilhodzic's side onto 20 points from nine games. With Saudi Arabia losing to the United Arab Emirates on Tuesday evening, the Japanese are now guaranteed first place in the group no matter what happens in the final round of matches next week.

Australia's hopes are now out of their own hands. Ange Postecoglou and his team need to beat Thailand in Melbourne on Tuesday, and hope Japan avoid defeat when they travel to face second-placed Saudi Arabia.

The Japanese, who have joined Iran in qualifying for next year's finals, were the only team to confirm their place in Russia on Thursday during another tense evening's action across Asia.