McKeown goes close to 100m backstroke world record in Sydney
The Australian 22-year-old touched in 57.57 seconds, just shy of her world best 57.33 as she ramps up preparations for the defence of her Olympic title in Paris.
She blitzed home at Sydney Olympic Park Aquatic Centre ahead of 200m freestyle world record holder Mollie O'Callaghan (58.71) and now owns all six quickest times in history.
McKeown is the first woman to hold world records in the three backstroke disciplines and will head to the Olympics as a raging favourite.
Fellow Olympic champion Ariarne Titmus took out the 400m freestyle title in 4:02.39, narrowly ahead of Lani Pallister (4:02.65) and more than eight seconds clear of third-placed Jamie Perkins.
Like McKeown, Titmus will be the woman to beat in Paris as the defending champion and world record holder who owns four of the six fastest times ever.
But American great Katie Ledecky and Canadian teenager Summer McIntosh will be key threats.
Olympic bronze medallist Emma McKeon clinched the 100m butterfly title in 57.37 but was relegated to joint second alongside O'Callaghan in the 50m freestyle by Bronte Campbell (24.64).
The NSW State Championships, which conclude on Sunday, are an important stepping stone towards Australia's Olympic trials in June.