Kaylee McKeown wins GOLD at the Olympic Games: Australian swimming gun gives nation much-needed boost after day to forget in Paris

Kaylee McKeown has defender her Olympic title to win gold again in a thrilling 100m backstroke final in Paris.

On a day where the women's rugby sevens team and trap shooter James Willett saw their medal hopes slip in emphatic fashion, McKeown kept her cool in a fiercely-fought race to take the top prize.

The 23-year-old edged the United States' world record holder Regan Smith in the final.

McKeown won in 57.33 seconds with Smith taking silver in 57.66.

McKeown is just the second woman to win consecutive 100m backstroke gold medals in Olympic history, following American Natalie Coughlin (2004, 2008).

'Oh, Kaylee, you are just extraordinary!' gushed Giaan Rooney on Nine. 

'She has been the most dominant backstroker in the world for a number of years now. And really, that's a performance deserving of her consistency over those last three years. Between Tokyo and now, she has just been amazing.'

The Queenslander collected gold in both the 100m and 200m backstroke events at the Tokyo Olympics three years ago.

She will begin the defence of her 200m crown on Thursday with heats and semi-finals ahead of Friday's medal race.

McKeown has also added the 200m individual medley to her Paris program, with the final of that event on Saturday.

McKeown now has four gold medals in her Olympic career after also featuring in Australia's triumphant women's 4x100 medley team in Tokyo.

She is also likely to feature in Australia's team in the medley final to be decided on Sunday's last day of competition at the Paris pool.

More to follow.