Although Michael Phelps retired seven years ago, his legacy has continued to tower over swimming.

But on Saturday, Phelps last remaining world record was smashed by 21-year-old Leon Marchand at the World Aquatics Championships in Fukoka, Japan, as the Frenchman completed the 400 meters individual medley in 4:02.50, shaving an enormous 1.34 seconds off Phelps previous mark.

That was insane, one of the most painful things Ive done. It was amazing to do it here and the time is crazy, Marchand said afterwards, according to the Olympics official website, The best is yet to come.

Marchand was just six years old when Phelps set the previous world record in the discipline, at the 2008 Beijing Olympics, and he was presented with the gold medal afterwards by the legendary American swimmer.

Phelps himself had held the world record for almost 21 years, setting a series of increasingly faster times during his stint as the worlds most dominant swimmer.

Its excellent, I train everyday for that, Marchand added. Im two seconds faster than my previous record, I beat the world record, its amazing¦ I dont know what to say, Im so happy.

The 21-year-old was under Phelps world record pace for the entirety of his swim, eventually finishing more than four seconds ahead of the USAs Carson Foster in second and almost seven seconds ahead of Japans Seto Daiya in third, as he secured his third ever gold medal at the world championships.

Meanwhile Australias Ariarne Titmus set a world record in the womens 400 meter freestyle with a time of 3:55.38, so blistering that she held off Katie Ledecky in second place. (CNN)