Moesch, a 20-year-old from the University of Virginia, clocked 51.94 seconds in her win at the AP Race London International this week, only the third sub-52 swim in history.

It was briefly the second-fastest ever, behind only Sjostrom’s world record of 51.71 set with the leadoff leg of the 4x100m relay at the 2017 world championships in Budapest.

On Wednesday, though, Moesch’s mark was bettered by world champion Steenbergen, who clocked 51.86 on the south coast of France at the Canet stop of the Mare Nostrum series.

Steenbergen finished seventh behind Sjostrom in the 100 final at the 2024 Paris Olympics but has been setting the standards since the Swede went on maternity leave.

She brushed off her Paris disappointment by successfully defending her world title in Singapore last year, edging Australia’s former world champion Mollie O’Callaghan.

Sjostrom, 32, returned to competition at a home meet last month but has focused on the 50m freestyle and butterfly as she builds towards the European championships in Paris in July-August.

For US swimming, Moesch’s rise may be a game-changer for a nation that has been foiled repeatedly by Australia’s women in the Olympic 4×100 relays.

The Americans were runners-up at Paris as Australia won a fourth successive gold medal in the event.

New Jersey native Moesch adds another weapon to a formidable US programme boasting the versatile Kate Douglass and Torri Huske, the individual 100m silver medallist at Paris.

Moesch swam a heat in the 100 relay at last year’s world championships but was dropped for the final as Simone Manuel, Douglass, Erin Gemmell and Huske finished second to Australia.

Australia’s women will provide a glimpse of their form midway through the Olympic cycle when they compete at national trials next month for the Glasgow Commonwealth Games starting on July 23.