[5] The Australian Defense — is an unorthodox chess opening in the Queen's Pawn Game, defined by the moves: 1. d4 Na6.

In tournaments, he repeatedly and effectively used this defense, although in general this debut at world-class competitions is extremely rare.

[7] The Australian Defense is described in his chess course by International Master (Grandmaster since 2022) Renato Quintiliano [pt] in 2018.

[9] Black's ideas in this defense are similar to White's Durkin Attack, the advantage of the opening is that the pawn structure is not affected.

It is recognized as somewhat dubious, but can transpose to the slightly more acceptable de Bruycker Defense in the Caro–Kann if the game continues 2. e4 c6.