Five-time Olympic gold medallist Kaylee McKeown has been given a reprieve after protesting her disqualification at Australia’s national swimming trials in Adelaide on Monday afternoon.

After winning the women’s 50-metre backstroke — an event for which she is the world record-holder — McKeown emerged from the pool to the news that she had been disqualified for early movement on the blocks.

The ruling had initially dashed her hopes of competing for a world championships gold medal in one of her signature events at Singapore later this year.

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But officials heard McKeown’s protest and accepted that she had been “distracted by a movement” on the blocks.

The 23-year-old’s lightning time of 27.27 did not come up on the board when she touched the wall to win her heat.

After the race, a Swimming Australia staff member consoled McKeown, who opted not to speak to media when she got out of the pool as she was ushered away in devastation.

The formal appeal issued by her team was later upheld though, granting McKeown the chance to compete in the final later on Monday night.

Mollie O’Callaghan qualified second with a time of 27.72, the only other swimmer to hit the world championships qualification standard, which is 27.74.

To earn selection for Singapore, swimmers must finish in the top two of their event and better the world championships standard.

Dolphins head coach Rohan Taylor expects an Australian team of about 44 swimmers for the July 27-August 3 event.

“In some events there will be a changing of the guard,” Taylor said.

“The inevitability is that some people vacated an event and we’re looking for the young ones to jump up ... it’s going to be exciting to see.

“You will see some shifts in, some newness, and that’s usually the case year one after the Olympic Games.”

After last year’s Paris Games, Australia’s most successful Olympian Emma McKeon retired with a collection of 14 Olympic medals featuring six gold.

Other Dolphins stalwarts including Mitch Larkin, Bronte Campbell, Madi Wilson, Brianna Throssell and Jenna Strauch have also quit.

Four-time Olympic gold medallist Ariarne Titmus — who on Sunday lost her women’s 400m freestyle world record to Canadian ace Summer McIntosh — will also skip this year’s worlds while on an extended post-Olympic break.

“Tokyo (Olympics) to Paris was a bit different because everybody was ‘well, it’s only three years, so we’ll stay in’,” Taylor said of the three-year gap between the 2021 Games in Japan to last year’s sporting showpiece in France.

“Now we have had obviously some senior athletes retire with glittering careers and well deserved - but the next opportunity pops up.”

- With AAP