Cameron McEvoy has become the first person to claim the national freestyle triple crown after taking 50m gold at the Rio trials in Adelaide on Wednesday night.
McEvoy clocked a personal best 21.44 seconds to win the 50m title ahead of Matt Abood (22.08).
James Magnussen (22.12) finished third, ensuring he must rely on being included in the 4x100m relay team to earn Rio selection. That appears likely.
Only a top two finish within the qualifying time secures an individual Rio nod.
It marked the first time someone had won the national 50m, 100m and 200m crowns at the same meet since the one-lap event was added to the program in 1983.
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McEvoy, 21, had earlier at the trials dead heated with Thomas Fraser-Holmes for the 200m gold and clocked the third fastest time ever to claim the 100m title.
The 50m event marked Magnussen's last chance to secure an individual swim in Rio, having missed a spot in his pet event, the 100m freestyle by placing fourth in the final.
The Rio team will be confirmed on Thursday.
Cate Campbell set a new Australian record (23.93) to be fastest qualifier for Thursday night's 50m freestyle final.
It was the fastest time in the world for the year.
World champion Bronte Campbell (24.27) was second fastest.
Belinda Hocking (2:06.49) booked her ticket for her third Olympic campaign when she upset world champion Emily Seebohm to claim the 200m backstroke title.
Former world No.1 Hocking's winning time was the fastest in the world for the year - an extraordinary achievement considering the 25-year-old had just come back from a six month sabbatical.
Jess Ashwood (8:18.42) defended her 800m freestyle title, falling 0.01 short of her Australian record.
Dual world champion Mitch Larkin (24.73) claimed the 50m backstroke title.
David Morgan (51.64) won the 100m butterfly title and Georgia Bohl (30.58) the 50m breaststroke crown.
