French youngster Leon Marchand set the world record in the men's 400-meter individual medley Sunday, breaking the last individual mark that Michael Phelps had held from his illustrious swimming career.
Marchand cruised to the gold medal in 4 minutes, 2.50 seconds at the world championships in Fukuoka in southwest Japan. That broke the long-standing mark of 4:03.84 set 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."
"The best is yet to come," added Marchand, who collected his medal at the victory ceremony from Phelps, who was in attendance as a television commentator.
Phelps had held individual world records in five different races. He still is part of the world records set by the United States in the 4x100 and 4x200 freestyle relays.
Marchand, 21, 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 and will also be the favorite in the 200 IM.
"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."
He finished 4.06 seconds ahead of silver medalist Carson Foster of the United States. Japan's Daiya Seto took the bronze, coming in nearly seven seconds behind Marchand.
It was the second of three world records to fall on the opening day of the swimming events at the World Aquatics Championships. Olympic champion Ariarne Titmus of Australia set the record in a star-filled women's 400-meter freestyle field with a time of 3:55.38, finishing more than three seconds ahead of Katie Ledecky. Australia also set the record in the 4x100 women's freestyle relay in 3:27.96.
In other results, Australia's Sam Short powered to victory in the men's 400 freestyle to dethrone compatriot Elijah Winnington.
Short, 19, crossed the line in 3:40.68 to narrowly beat Olympic champion Ahmed Hafnaoui of Tunisia by 0.02 seconds. Germany's Lukas Martens was 1.52 seconds behind to take the bronze medal.
"I had goosebumps thinking I was in the race with him and got my hand on the wall first," Short said of racing Hafnaoui. "... Dream come true."
Winnington, who won the title in Budapest last year, was seventh out of eight competitors.
In the 4x100 men's freestyle relay, Australia took the gold in 3:10.16, with Italy earning the silver (3:10.49) and the United States the bronze (3:10.81) as all three countries automatically qualified for the Paris Games.
The British men's team, the pre-meet favorite, did not compete after being disqualified due to an early takeoff by Jacob Whittle in their morning heat.
Reuters and The Associated Press contributed to this report.