Léon Marchand, world champion in the 400m medley on Saturday, achieved the 4th time in the half (1 min 54.32), beating the French record held by Franck Esposito (1 min 54.62) since 1971.
The Hungarian Kristof Milak recorded the best time (1 min 52.39).
At 20, the Toulousain will try to win the second world title of his young career on Tuesday.
No worries either for Charlotte Bonnet, qualified a little earlier for the 200m freestyle final.
The 27-year-old swimmer came 4th in the semi-finals with a time of 1 min 56 sec 54/100.
It was Briton Freya Anderson who set the fastest time (1 min 56.05).
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