Mollie O'Callaghan breaks world record, Regan Smith ties world record at Westmont World Cup

Australian Mollie O'Callaghan broke the short-course world record in the 200m freestyle at a World Cup in Westmont, Illinois, on Saturday.

O'Callaghan, the Olympic and world champion in the event in long course (50-meter pools), swam 1:49.77 in the 25-meter pool.

She lowered the world record of 1:50.31 by Hong Kong's Siobhan Haughey from 2021.

Also Saturday, American Regan Smith tied her short-course world record of 54.02 in the 100m backstroke, defeating Olympic and world champion Kaylee McKeown of Australia (55.04).

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American Gretchen Walsh swam the second-fastest 50m butterfly ever (23.90), just missing her world record of 23.72 from last week. Walsh owns the top nine times in history.

The Westmont World Cup concludes Sunday with prelims (11 a.m. ET) and finals (7 p.m.) live on Peacock.

Ariarne Titmus retires from swimming

Ariarne Titmus won four Olympic gold medals for Australia.

• Nick Zaccardi,