Kyle Chalmers has already made a splash in his Tokyo Olympics campaign, helping Australia win bronze in the men's 4x100m freestyle relay.
Chalmers, who grew up in Port Lincoln, swam for Australia in the relay heats on Sunday evening, where Australia qualified third fastest behind Italy and the United States.
Joining Chalmers in the final would be Zac Incerti and Alexander Graham, with Matt Temple selected in place of Cam McEvoy.
Temple started the swim and had a big task as the United States, who were favoured for this event, led with Caeleb Dressel, who led at the first change over Maxime Grousset of France and Andrei Minakov of Russian Olympic Committee, with Temple hitting the wall in sixth.
Incerti brought Australia into fifth at his change and Graham would hit the wall with Australia in sixth, bringing Chalmers into the race.
With Australia in sixth place for the final leg, Chalmers would record one of the fastest splits in the event's history, 46.44 to bring Australia into third, with the United States winning the gold and Italy the silver.
This is Chalmers' fourth Olympic medal, following his two bronze and gold achieved at Rio de Janeiro in 2016.
Two of Chalmers' supporters who was delighted with the result were his grandparents Malcolm and Julie Bagnell, who live in Port Lincoln.
Mr Bagnell said the swim was "amazing to see" and while they knew the Americans would be hard to beat, they were amazed with how Chalmers lifted.
"He just swam his heart out again for us all and it certainly made our day," he said.
Mr Bagnell said the heats for the relay were on his birthday so Chalmers said he would give him a "good birthday swim", which he did to help Australia get into the final.
Chalmers is the reigning Olympic champion in the men's 100m freestyle and will begin his attempt to defend his crown in the heats, which will take place Tuesday evening.
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