Maxime Grousset shaved 0.06secs off his prelims time to go 48.03 in the 100 free at the French Elite Championships in Limoges.
The 22-year-old – who was fourth in Tokyo – went 48.09 in the morning heats to replace Lewis Burras at the top of the world rankings despite the Briton coming within 0.06secs in 48.15 at his own national championships about an hour later.
Grousset, who claimed the 50 fly spot for Budapest ahead of 2015 world champion Florent Manaudou earlier in the week, returned in the evening to lower that further in a world-leading time.
Out in 23.33 and back in 24.70, Grousset enjoyed a clear margin of victory over second-placed Hadrian Salvan whose time of 48.51 was also inside the cut of 48.77. Charles Rihoux was third in 49.25.
Charlotte Bonnet elevated herself into the world top five with 1:56.47 over 200 free.
The 2018 European champion split 27.05/56.71/1:26.82 before coming home in 29.65 to go fourth in the world rankings headed by Ariarne Titmus and her time of 1:54.66.
Oceane Carnez (1:59.70) and Lucile Tessariol (2:00.22) completed the podium.
Mary-Ambre Moluh set her second age group record of the meet as she went 27.70 in the 50 back.
It qualified the 16-year-old – who does not turn 17 until September – for her second event at world titles to add to the 100 back with Analia Pigree also inside the cut of 28.22 in 27.72.
Beryl Gastaldello was third in 28.22.
Damien Joly won the men’s 800 free in 7:51.25 – well within the cut of 7:53.11 – ahead of Joris Bouchaut (7:54.37) and Logan Fontaine (7:54.71).
Noyan Taylan overhauled Algeria’s Jaouad Syoud on the third 50 to claim the 200 fly title in 1:57.23 to 1:57.88. Clement Secchi was third in 1:58.72.
Antoine Viquerat edged Carl Aitkaci by 0.02 in the men’s 50 breaststroke, winning in 27.92 to 27.94 with Manaudou third in 28.23.