French swimmer breaks Michael Phelps' last individual record

French swimmer Leon Marchand broke Michael Phelps' last individual world record on Sunday, winning the 400-meter individual medley at the world championships in Fukuoka, Japan.

Marchand, 21, captured the gold medal in 4 minutes and 2.5 seconds, eclipsing the mark of 4:03.84 established by Phelps at the 2008 Beijing Olympics.

"That was insane, one of the most painful things I've done," Marchand said. "It was amazing to do it here, and the time is crazy."

Marchand trains at Arizona State under Phelps' longtime coach, Bob Bowman.

Phelps, 38, had held the 400-meter IM record since 2002. He was in attendance as his record fell, calling the race for NBC Sports.

At one point, Phelps held individual world records in five races. He still holds the records with the U.S team in the 4x100 and 4x200 freestyle relays.

Phelps won a remarkable 28 medals across five Olympics -- 23 of them gold.