Emma McKeon joins Aussie greats with incredible 100m freestyle gold

Emma McKeon has claimed her fourth medal of the Tokyo Olympics, winning gold in the 100m freestyle final in an Olympic record.

McKeon entered Friday's final as red-hot favourite after qualifying fastest.

'SO SAD': Olympics rocked by death of 19-year-old youth athlete

CLASS: Ash Barty's stunning act amid Olympic Games heartbreak

And she lived up to the hype in a pulsating final, with compatriot Cate Campbell winning bronze.

McKeon's second gold is her fourth medal at the Tokyo Games - having already triumphed in the 4x100m freestyle relay, as well as bronzes in the 100m butterfly and 4x200m freestyle relay.

It made McKeon the first athlete at the Tokyo Games to win four medals.

"I can't believe it, it doesn't feel real," McKeon told Channel 7.

McKeon and Campbell became the first Australian women to medal in the same 100m freestyle final since the 1956 Olympics.

McKeon now has eight Olympic medals, equalling Dawn Fraser, Petria Thomas and Susie O'Neill.

She is just one medal shy of equalling the record of Ian Thorpe and Shane Gould for most medals by an Australia at a single Olympics - five.

McKeon won Friday's final in 51.96 seconds followed by Siobhan Haughey (52.27) from Hong Kong and Campbell (52.52).

The 27-year-old led from start to finish: she was first off the blocks in a reaction time a tenth of a second quicker than any rival.

McKeon led at the halfway stage and maintained her dominance until the wall.

Australia erupts over incredible Emma McKeon swim

She is also favourite for the 50m freestyle, with heats in that sprint are contested on Friday night.

And McKeon is likely to feature when Australia contends for a 4x100m mixed medley medal, which could give her a record sixth medal of the Games.

Swim legends Gould and Thorpe hold the Australian record for the most medals at one Games with five each.

Thorpe won three gold and two silver in the Sydney 2000 Games while Gould collected three gold, one silver and a bronze at the 1972 Munich Olympics.

And should McKeon win six medals, her Olympic career total of nine will equal Thorpe's record for most by an Australian.

It marks Australia's ninth gold medal of the Games.

The country erupted on social media over the historic achievement.

with AAP

Watch 'Mind Games', the new series from Yahoo Sport Australia exploring the often brutal mental toil elite athletes go through in pursuit of greatness:

Click here to sign up to our newsletter for all the latest and breaking stories from Australia and around the world.