Daniel Fitzgibbon and Liesl Tesch enjoyed another strong day to finish six points ahead of the fleet with a single race scheduled for tomorrow.
The pair revelled in the stronger breeze and left their rivals in their wake in the first race, leading at every mark to record their fourth victory of the series so far.
The second race of the day was sailed in lower winds of around 12 knots, conditions that clearly suited the Italian crew of Marco Gualandris and Marta Zanetti, who shot off the start line into a lead they held to the finish.
The Australians are now uncatchable in the overall lead of the class, but the final day will determine the destination of silver and bronze.
The USA pair of Jen French and JP Creignou are in second and Great Britain's Alexandra Rickham and Niki Birrell two points behind in third.
In the Single-Person Keelboat (2.4mR) Great Britain's Helena Lucas remains on course for gold and is guaranteed to leave London 2012 with at least a silver medal.
The 37-year-old finished eighth and fifth today to give her a nine-point cushion over second-place German Heiko Kroger heading into tomorrow's final race. Thierry Schmitter lies third.
Lucas, the only woman in the fleet, is guaranteed silver and looks good for gold, meaning Britain are sure to win their first medal since Sailing joined the Paralympic programme in 2000.
In the Three-Person Keelboat (Sonar), there were three races today - two of which were won by Norway and one by the Netherlands.
The Netherlands have an unassailable 20-point lead going into tomorrow's final race, followed by Germany in second place.
Great Britain slipped back from third to fifth overall after they collected a four-point penalty. Norway have moved up to third spot.