Rhyan Grant's header earned Australia back-to-back victories in the final phase of Asia's World Cup preliminaries as Graham Arnold's side defeated Vietnam 1-0 on Tuesday and South Korea secured three points with a 1-0 win over Lebanon.
The Socceroos followed up their comfortable win over China on Thursday with a workmanlike performance in Hanoi to maintain their perfect start to the 2022 World Cup qualifiers.
Australia's 10th successive win in all phases of qualifying moved them to six points on top of the Group B standings.
Australia are aiming to progress to a fifth straight World Cup -- and sixth in total -- with the first two teams in each of Asia's two qualifying groups advancing automatically to the finals in Qatar.
Grant scored the winner two minutes before half-time when Ajdin Hrustic's ball swung over the Vietnamese defence and the unmarked Sydney FC defender headed across Dang Van Lam and into the corner.
The goal came after Vietnam's Nguyen Quang Hai squandered an early opportunity, failing to show the accuracy that allowed him to net in his side's loss to Saudi Arabia last week.
Grant cut a relieved figure in the 29th minute when referee Abdulrahman Al Jassim decided not to award the home side a penalty after Nguyen Phong Hong Duy's shot struck him on the arm.
Mitchell Duke thought he had given Australia a scarcely deserved second late in the game, only for his effort to be ruled out for offside.
The South Koreans, meanwhile, secured their first win in Group B as Paulo Bento's side saw off Lebanon in Suwon.