Michael Phelps paid tribute to Hungarian teenager Kristof Milak's "beautiful technique" after he took down the American legend's long-standing 200 metres butterfly record at the world championships in South Korea.
Phelps described Milak's time of one minute, 50.73 seconds in Gwangju as "incredible", although he admitted his astonishment was tinged with sadness at losing a world record which had stood since 2009.
"As frustrated as I am to see that record go down, I couldn't be happier to see how he did it," Phelps told the New York Times.
"That kid's last 100 was incredible. He put together a great 200 fly from start to finish."
"(He) worked on his technique until it was beautiful and put in the really, really hard work that it takes to do it -- my hat's off to him."
Le Clos, who famously beat Phelps in the 2012 London Olympic final, shrugged: "Kristof is in another league -- he's a hell of a lot faster than all of us."