Australia broke the previous best time by 1.46 seconds as they eased to victory over Germany and Canada, who did enough to book their own passage to the next round.
Great Britain have dominated the men's Four over the last 12 years, winning gold in Sydney, Athens and Beijing.
But the Australian crew, who won last month's Munich World Cup regatta, are now a real threat.
'To lay the heat out that way gives us some confidence and sets us right up for the rest of the week,' said Australian veteran Drew Ginn, who is chasing a fourth Olympic gold medal.
We are trying to go out as fast as possible from stroke one. We are not playing games in racesDrew Ginn
'We are trying to go out as fast as possible from stroke one. We are not playing games in races.'
Britain won their heat in commanding fashion and the USA also got their campaign off to a victorious start.
The other Olympic best time to fall on Day 3 went to Great Britain's Double Scull of Katherine Grainger and Anna Watkins.
The gold medal favourites stormed into Friday's final ahead of defending champions New Zealand, who also qualified.
Australia's Kim Crow and Brooke Pratley also bettered the old best, which had stood for 20 years, in winning their heat ahead of Poland.
The men's Eight final line-up was completed with Great Britain winning the repechage ahead of reigning champions Canada, who also qualified along with Netherlands and Australia.
The quartet joined favourites Germany, who are unbeaten since 2009, and the USA in the final after they qualified directly from the heats.
Reigning Olympic champions China finished fourth in the women's Quadruple Sculls repechage to squeeze into the final, along with race winners Australia, the United States and Great Britain.
New Zealand were on course to qualify until they suffered a broken oar with around 400m to go, allowing Great Britain back into the race.
Two-time Olympic champions Romania won the women's Pair repechage to reach Wednesday's final, along with second-placed Germany.