Rapid O'Callaghan upstages Titmus to send Paris Olympic warning

SYDNEY - World record-holder Mollie O'Callaghan upstaged Olympic champion Ariarne Titmus to win the 200m freestyle in the fastest time this year at Australia's NSW State Championships on Sunday.

The 19-year-old hit the wall in 1min 54.76secs, which would have earned her gold at the world championships in February, an event she skipped to focus on this summer's Paris Olympics.

Titmus (1:55.81) came second in a stacked field that saw Lani Pallister (1:55.92) touch third and all-conquering backstroke star Kaylee McKeown finish fourth in a lifetime best of 1:56.06.

While O'Callaghan holds the world record with 1:52.85, Titmus owns three of the top-five quickest times in history, putting them on course for a blockbuster showdown in Paris.

Canadian teenager Summer McIntosh and Hong Kong's Siobhan Haughey are also set to be in the Olympic mix.

McKeown -- who holds world records in all three backstroke disciplines -- showed off her versatility by backing up to win the 200m medley in 2:08.84.

Just minutes later, the 22-year-old was back in the Sydney Olympic Park Aquatic Centre pool to easily clinch the 50m backstroke title in 27.25, with only Canada's Kylie Masse swimming faster this year.

The three-day NSW State Championships, which ended Sunday, are an important stepping stone towards Australia's Olympic trials in June.