Australia surged past the United States in the final leg of the open water relay to make a winning start in the head-to-head duel with their swimming rivals in Sydney.
The showdown between the code's superpowers kicked off with a 4x800m open water relay off Bondi Beach, won narrowly by Australia after Kyle Lee proved too strong for Tylor Mathieu.
Lee entered the water 18 seconds behind Mathieu and trailed by nine seconds halfway into the final leg, before taking the lead with 20m remaining and holding on to claim crucial Duel in the Pool points.
"My team put me in a very good position," Lee said. "I wasn't sure if I'd be able to get them but I just tried to do my best and catch them.
"It was a pretty close finish. Once I went past Tylor I could see that she was still at my feet so I knew I couldn't back off at the end."
Australia opened with their two female freestylers Chelsea Gubecka and Kareena Lee in the mixed relay while the US made a fast start with male swimmers Charlie Clark and David Johnston.
Kai Edwards pulled back the margin slightly on the third leg against the 17-year-old US star Bella Sims, but Kyle Lee still had plenty to do to claim the win.
Australia poured talent into their open water team with long distance swimming Olympians in Gubecka, Edwards and Kareena Lee in their overall event squad of 30.
Kyle Lee is targeting a first Olympics appearance at Paris in 2024 and showed in Bondi he's still holding the form that led him to fifth over 25km and eight over 5km races at the recent world championships.
The 20-year-old will also swim the broken freestyle at the Duel in the Pool event.
"At the world champs I did the 25km, so this was definitely something different," Lee said.
"We train for the longer-distance events so the back end of our race was going to be our stronger point."
While this is the fourth time Australia has faced the US in a Duel in the Pool meet - the last time was in Sydney in 2007 - this is the first clash to include an open-water event.
The Duel in the Pool now heads to Sydney Olympic Park Aquatic Centre on Saturday and Sunday nights for traditional and experimental races involving swim stars like Emma McKeon, Kaylee McKeown, Mollie O'Callaghan and Zac Stubblety-Cook.
