The 18-year-old world junior champion stormed home after turning in seventh place to get his hands on the wall first in a blanket finish. 

He won in a personal best time of 47.58 seconds, just 22-hundredths of a second ahead of Belgian silver medallist Pieter Timmers and 0.27 in front of American Nathan Adrian, the gold medallist in London four years ago.

The last Australian to win the Olympic gold was Mike Wenden, at Mexico City in 1968. 

For a country surrounded by water and obsessed with swimming, the wait for a successor in swimming's showpiece event has been an unfathomable source of national frustration.

Four years ago in London, Australia's James Magnussen suffered an agonising defeat to Adrian, losing the gold by just one one-hundredth of a second in the closest 100m free Olympic final ever.