Alex de Minaur and Lleyton Hewitt go wild after seeing Kaylee McKeown become back-to-back Olympic Games champion

Alex de Minaur's Olympic Games journey may be over, but the Aussie tennis star has stuck around in Paris to cheer on his compatriots.

And the 25-year-old, along with coach and Aussie tennis legend Lleyton Hewitt, went absolutely wild when they saw Kaylee McKeown become a back-to-back Olympic champion in Paris.

De Minaur and Hewitt formed an Aussie contingent cheering on McKeown and teammate Iona Anderson on Tuesday night (local time), with the gun duo competing in a strong field that contained Team USA's world record holder Regan Smith. 

It wasn't to be for Anderson, but McKeown kept her cool in a closely-fought race to touch the wall ahead of her American rival to add to her collection of three gold medals.

After showing McKeown slamming the surface of the water in jubilation, the camera panned to De Minaur and Hewitt in the crowd, with both going bananas. 

De Minaur pulled out of the men's singles competition in Paris, citing a hip injury he picked up during his run at Wimbledon this month.

He featured in the men's doubles alongside childhood friend Alexei Popyrin, but the pair were eliminated in the first round. 

De Minaur's tennis star girlfriend, Katie Boulter, was in action earlier on Tuesday, winning her women's doubles match against Germany alongside Heather Watson. 

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

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.