French star Leon Marchand breaks Michael Phelps' last individual world record, the 400m IM

French 22-year-old Leon Marchand has broken Michael Phelps' world record in the men's 400-meter individual medley in a time of 4 minutes, 2.50 seconds. 

Phelps set the old record of 4:03.84 at the 2008 Beijing Olympics.

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

It was the last individual record that Phelps held since retiring for good after the 2016 Rio de Janeiro Olympics.

Marchand swims at Arizona State and is coached by Bob Bowman, the coach of the American team at the world championships. He is a potential hometown superstar going into next year's Paris Olympics. He will also be the favorite in the 200 IM.

"That was insane," Marchand said after the race, obliterating Phelps' record by more than a second. "That was one of the most painful things. That was just amazing to do it here. I mean, the time is crazy."

Marchand then added: "The best is yet to come."

Phelps, in Japan to comment for television, presented the gold medal to Marchand. He said Phelps offered a tip, which was to finish his freestyle leg faster.

"He (Phelps) was very impressed by the time," Marchand said. "He was commenting the race. It was pretty cool to see that."

Marchand is coached at Arizona State University by Bob Bowman, who is also the head coach of the American team at the worlds and also coached Phelps.

Marchand said he's prepared for the pressure of next year's Paris Olympics where he is sure to be the face of the French Games.

"I think I can handle the pressure pretty well right now," Marchand said. "It's not perfect and I can get better and I have one year to improve."