GWANGJU, South Korea -- Caeleb Dressel broke Michael Phelps' world record in the 100-meter butterfly Friday at the swimming world championships.
The American won his semifinal heat in 49.50 seconds -- 0.32 seconds better than Phelps' mark set at the 2009 world meet in Rome at the height of the high-tech suit era.
Dressel was out in 22.83 seconds -- 0.53 seconds under Phelps' pace -- and came home in 26.67 to lead eight men into Saturday's final.
He was a whopping 1.44 seconds ahead of Andrei Minakov of Russia, the second-quickest qualifier.
"Just the standard that Michael set, wanted to go after it," Dressel said. "I hope he was happy watching me do that."
It's the second world record of Phelps' to fall at this year's worlds. Kristof Milak of Hungary won the 200 fly in 1:50.73, bettering Phelps' mark of 1:51.51, also set in Rome.
Anton Chupkov of Russia also broke a world record Friday, doing so in the men's 200-meter breaststroke final.
He won gold in 2:06.12, defending his title from two years ago in Budapest. That lowered the mark of 2:06.67 that Matthew Wilson of Australia had tied in the semifinals a day earlier. Ippei Watanabe of Japan set the mark in January 2017 in Tokyo.
Chupkov was eighth after the first lap and moved up to fifth at 150 meters. He came home in 31.89 to overtake Wilson, who led from the start.
It was the third world record of the night in Gwangju.
Mack Horton rallied Australia to victory in the men's 4x200 freestyle relay, putting them in front with a lap to go. Clyde Lewis, Kyle Chalmers, Alexander Graham and Horton won in 7:00.85.
Russia took silver in 7:01.81. The U.S. team of Andrew Seliskar, Blake Pieroni, Zach Apple and Townley Haas earned bronze in 7:01.98.
Sun Yang swam China's anchor leg against Horton, but he wasn't able to move his team up and it finished sixth in his final event at worlds.
Evgeny Rylov of Russia defended his 200 backstroke title, beating Olympic champion Ryan Murphy after the two dueled through the closing meters.
Rylov led all the way and touched in 1:53.40. Murphy settled for silver in 1:54.12. Luke Greenbank of Britain earned bronze.
Information from The Associated Press was used in this report.