Alicia Coutts, Cate Campbell, Brittany Elmslie and Melanie Schlanger saved their best until last.
The quartet won Australia's first gold in London after taking out the women's 4x100m freestyle relay in Olympic record time in the final event of the first finals session.
The Aussies left defending champions the Netherlands in their wake as they clocked a red-hot 3:33.15secs, which was 0.61secs better than the mark set by the Dutch in Beijing four years ago.
Hot favourites before the event, the Dutch had to settle for silver, while the US finished with bronze.Coutts (53.90) got the Aussies off to a good start by touching in third, Campbell (53.19) elevated them to second, before Elmslie (53.41) propelled them to the lead.
Then Schlanger (52.65) hung on against the fast finishing Dutch world champion Ranomi Kromodwidjojo (51.93).
The victory also meant Libby Trickett added a fourth gold medal to her career tally after she swam in the morning heats. Only Dawn Fraser has won as many gold medals.
But it wasn't all good news for Australia in the pool.
Thomas Fraser-Holmes finished seventh in the men's 400m individual medley as American superstar Ryan Lochte destroyed the field.
The fact Lochtie won was no surprise, the fact superstar countryman Michael Phelps could only manage fourth was a shock to many.
The winner of a record eight gold medals in Beijing, Phelps was lucky to qualify for the final, scraping in with the eight-fastest heat time.
Lochte led from start to finish to touch the wall in 4:05.18secs - the second fastest time in history.
Aussie Olympic debutant Ryan Napoleon finished eighth in the final of the men's 400m freestyle, which was won by Chinese 1500m world record holder Sun Yang. Yang clocked 3:40.14secs, a personal best and the third fastest time in history.
Golden girl Stephanie Rice couldn't repeat her heroics from Beijing. She finished sixth in the 400m individual medley and lost her world record in the process to Chinese star Ye Shiwen.
Ye clocked a stunning 4:28.43secs to slash 1.02 seconds from the record Rice set to win gold in Beijing in 2008.
The 16-year-old was almost a second behind race leader, American world champion Elizabeth Beisel, with 100m to swim, but flew past her in the freestyle leg.Beisel (4:31.27) finished second with another Chinese teenager, Li Xuanxu (4:32.91) snaring bronze (4:32.91). Rice finished with a time of 4:35.49secs.
After the race, the Queenslander, who has been troubled by shoulder injuries since Beijing, said she knew she had the job ahead of her, but had given it her all.
"I knew this race was going to be hard. More than anything I'm a little disappointed with the time, but all I wanted to do was give it my best shot," Rice said.
"I walk away from this race not being able to give any more.
"I'm disappointed with the time but I am not disappointed with the effort I put in. I raced the best I could tonight."