Malcolm Page and Mathew Belcher won the men's 470 dinghy gold medal on Friday, ensuring Australia will topple hosts Great Britain and finish on top of the Olympic sailing regatta medal table.
Page also cemented his place in history as Australia's most successful Olympic sailor, claiming his second gold medal.
The reigning world champions started Friday's extremely tense medal race on Weymouth Bay already assured of a silver medal and with British pair Luke Patience and Stuart Bithell the only other crew challenging for the gold.
The Britons had to finish the race two boats ahead of Page and Belcher to snatch victory.
But the Australians sailed brilliantly in the light winds and finished the race second, with Patience and Bithell fourth.
Argentina took the bronze medal.
The result means Page, already acknowledged as the best 470 sailor in the world, becomes the first Australian sailor to win two Olympic gold medals.
He took the men's 470 gold medal in Beijing with former crewmate Nathan Wilmot.
London was Belcher's first Olympics, having teamed up with Page in 2009.
Australia have now won three gold medals at the Olympic regatta, with Tom Slingsby winning the Laser class and Nathan Outteridge and Iain Jensen taking victory in the 49er skiff.
It is the nation's most successful sport at the London Games.
No Australian sailing squad has ever won three gold medals at an Olympic regatta before.
The previous best was two golds, one silver and one bronze in Sydney 2000 and two golds and one silver in Beijing 2008.
It means Australia tops the London Olympic regatta medal table, condemning Great Britain to second place in home waters after topping every the sailing medal table at every Olympics since Sydney 2000.
And Australia's medal tally could rise even further in Weymouth, with the women's match racing crew competing in a semi-final battle with Finland on Friday afternoon, ahead of Saturday's final.
The Australian women's 470 crew also has an outside chance of snatching a bronze medal on Friday.
