World record-holder Kaylee McKeown ramped up preparations for the defence of her Olympic 100m backstroke crown with the second-fastest swim of all time on Tuesday.

The 22-year-old blitzed home at the Australian Olympic trials in 57.41secs, just shy of her world-record 57.33 and ahead of Mollie O`Callaghan who became only the fourth swimmer ever to dip below 58. O`Callaghan`s 57.88 in Brisbane was enough to also easily qualify, but she may not swim the event in Paris this summer given her likely heavy freestyle and relay schedule.