At 17, the recent double world champion erased from the shelves the mark of the Brazilian Cesar Cielo, who had held since 2009, by winning in 46.86, or 5 hundredths better.
He beat Hungarian Kristof Milak (47.47) and Italian Alessandro Miressi (47.63), Frenchman Maxime Grousset having to settle for 4th place.
Popovici, crowned at the Budapest Worlds in the 100 and 200 meters freestyle, has therefore erased the world record achieved in combination - a bygone era - by Cielo thirteen years ago.
Friday in the semi-final, in a time of 46 sec 98, the native of Bucharest became the fourth man only to go under 47 seconds behind Cielo, the Frenchman Alain Bernard (46.94) and the American Caeleb Dressel (46.98).
Note that Bernard's brand had not been officially approved due to an invalid combination.
Revealed at the European Junior Championships last summer, already in Rome, Popovici confirmed a few weeks later at the Tokyo Olympics.
When he was only 16 years old, he failed to 2 hundredths of bronze in the final of the 200m freestyle before taking seventh place in the final of the 100m freestyle.
His progress has not stopped.
In Budapest last June, he became the first man to complete the 100-200m freestyle double at the World Championships in nearly fifty years.
His performance on Saturday in the Olympic pool at the Foro Italico in Rome finally put him at the top of world men's swimming.
© 2022 AFP