Sydney (AFP) - Michael Andrew, Shaine Casas and teenage sensation Bella Sims all clocked victories as the United States inched ahead at the rekindled "Duel in the Pool" against Australia on Saturday.
Australia won the open-water race at Bondi Beach on Friday but the US took charge at the Sydney Aquatic Centre to lead 159-148 heading into the final day Sunday.
Centred around sprint events, Duel in the Pool took place every two years from 2003 to 2015, with points accumulated across individual and relay events.
The United States remain undefeated in seven editions -- the first three raced against Australia and the next four against teams drawn from Europe.
Andrew touched first in 59.77 seconds to claim the men's 100m breaststroke, leaving Australian 200m world record holder Zac Stubblety-Cook in his wake.
With Olympic 100m butterfly champion Caeleb Dressel not on the USA team, compatriot Casas took charge with a blistering 50.86 to win ahead of Australia's Matt Temple.
"Pretty happy with that time.Got my job done," said Casas.
Sims, 17, stormed to the women's 200m freestyle in 1:57.75, hitting the wall fractionally ahead of Australia's Lani Pallister.
Meg Harris (24.44) and Madi Wilson led an Australia 1-2 in the 50m freestyle while world champion Mollie O'Callaghan anchored Australia to victory in the 4x100m freestyle relay.
O'Callaghan also joined Emma McKeon to ensure Australia won the mixed 100m medley relay in 3:42.29.
"I haven't raced in front of this many people in Australia for a long time, so awesome," said McKeon, who made Commonwealth Games history this month by winning her 20th medal.
O'Callaghan, the 100m freestyle world champion, added: "Feels pretty sick.Nice to come back after a big few months and do it in front this sort of crowd."
Triple Tokyo Olympic gold medallist Kaylee McKeown touched in 58.73secs ahead of teammate O'Callaghan to comfortably win the women's 100m backstroke.
"I'm really happy with how I've been swimming this year, to be consistent and on podiums alongside my teammates is awesome," she said.
As well as seven traditional events, the quirky schedule, designed to add fun and excitement, included "mystery" medley races in which the order of strokes was randomly determined at the start.
There were also "broken" 400m and 800m freestyles where swimmers stopped at certain distances to earn points.The 400m free had a 200m race, followed by a pair of 100m races, with points awarded to the winner of each.
