Australian Olympic champion Kaylee McKeown has claimed a new short-course world record over American rival Regan Smith at a World Cup event in the US.

A day after compatriot Mollie O’Callaghan became the first woman to swim sub 1:50 in the 200m freestyle , McKeown repeated the dose with the first sub 1:58 in the 200m backstroke.

McKeown touched the wall in 1:57.87 to secure a $US10,000 ($A15,000) bonus — but it was seriously close.

Smith finished just behind in 1:57.91 to also go lower than her old world record of 1:58.04.

McKeown’s triumph turned the tables from 24 hours earlier when Smith matched her own 100m backstroke world record, winning in 54.02 with McKeown second (55.04). Loading content...

This week’s event in Illinois is the middle leg of a three-week World Cup tour of N

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