Marchand set the record on the first day of eight in the pool at the World Aquatics Championships - Fukuoka 2023.

Under World Record pace throughout the swim, the now-two-time 400m IM world champion left no doubt about the race's outcome with his breaststroke leg. 

Phelps had been the World Record-holder in the men's 400m IM since 15 August 2022, the longest uninterrupted streak in swimming history in the 50m pool. 

The 21-year-old Frenchman trains at Arizona State under Phelps’ career-long coach Bob Bowman.

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