With the only two women ever to have raced sub-1:52.5 on its side in a world where no others still in the fight have got, Australia looked quids in for the win.

It's never that easy, of course: one wrong call, as Tokyo showed when the Dolphins got bronze when they might have done better, can make all the difference.

Today, there were no missteps. Mollie O'Callaghan, Lani Pallister, Brianna Throssell and Ariarne Titmus rolled like Thunder from Down Under to the first sub-7:40 ever seen in Olympic waters, a Games record of 7:38.08, just 0.58sec shy of the World record set in a pool 3m deep at the World Championships in Fukuoka last year.

The race has been swum at the Games since 1996 and since then the USA has won 5 titles and no other nation had more than 1. Now, Australia has 2.

The USA took silver in 7:40.86 and China, having lost the title they claimed in World record time in Tokyo, the bronze in 7:42.34.