Caeleb Dressel breaks Michael Phelps’ world record in the 100 butterfly

GWANGJU, South Korea — Caeleb Dressel broke Michael Phelps’ world record in the 100-meter butterfly on Friday at the world swimming 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 1.44 seconds ahead of Andrei Minakov of Russia, the second-quickest qualifier.

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.

Also on Friday, Regan Smith broke the world record in the women’s 200-meter backstroke. The 17-year-old American won her semifinal heat in 2 minutes, 3.35 seconds. That erased the old mark of 2:04.06 set by Missy Franklin at the 2012 London Olympics.

Smith lowered her own junior world record in the morning preliminaries, finishing in 2:06.01. In the semifinals, she finished 3.22 seconds ahead of Kylie Masse of Canada, who was the second-fastest qualifier.