BUDAPEST • After Caeleb Dressel - one of the veterans expected to dominate the swimming world championships - quit the competition on Wednesday, two teenagers, David Popovici, 17, and Summer McIntosh, 15, leapt to the top step of the podium.
Dressel, a seven-gold Olympian, had "withdrawn for medical reasons, for his long-term health", according to Lindsay Mintenko, the swimming managing director for the United States team.
Romania's Popovici then claimed victory in one of Dressel's events, the men's 100m freestyle, and McIntosh of Canada won the women's 200m butterfly.
The evening ended with another of the US team's veteran stars, Katie Ledecky, carving a place in the record books with the victorious women's 200m relay team.
It was her 21st world championship medal, more than any other woman. Australia took the silver while Canada, with the help of McIntosh, held on for the bronze.
Dressel had already won two golds in Budapest before his last race on Tuesday morning. It was the 100m freestyle heats and the Olympic champion qualified only second fastest behind Popovici.
The teenager was asked after the final if he had scared off Dressel.
"I don't think so, I think he is too big of a boy to be running away from someone like myself or frankly anyone. But I hope he's OK and I hope he'll come back stronger," he said.
Popovici, who had become the first Romanian man to win a world title when he took the 200m free, became the first man to do the 100-200 freestyle double at the world championships since American Jim Montgomery in 1973.
"I'm glad we got to write a small page in swimming history," he added. "Some would say a huge page, but we like to keep it low key. I'm glad to have got two golds now... it will be pretty heavy carrying them."
His time of 47.58sec edged out Frenchman Maxime Grousset by just 0.06sec and Canadian Joshua Liendo Edwards by 0.13sec.
"In the 200, I was surprised by how much I won by (1.26sec). This time I was surprised by how little we won by," he said, adding he preferred the 200m event because it is more of a "smart race".
In the two-lap 100m, he explained, "we have to go out as fast as we can and come back as fast as possible. It's an animal instinct race".
McIntosh broke the world junior record with her 2min 5.20sec effort as she added the 200m butterfly to her silver from the 400m freestyle. She beat American Hali Flickinger with Zhang Yufei of China third.
"I just literally gave it my all and did everything I could, and put in all my energy and all my focus, and just stretched for the wall and put my hand on the wall as fast as I possibly could," McIntosh said.
In yesterday's finals, another teen - 18-year-old Australian Mollie O'Callaghan - won thewomen's 100m free in 52.67sec, ahead of Sarah Sjostrom (52.80sec) and American Torri Huske (52.92sec).
Ryan Murphy (1:54.52) won the men's 200m backstroke, while Lilly King clinched the women's 200m breaststroke in 2:22.41.
Meanwhile, Australian swimmer Shayna Jack, 23, was forced to withdraw from the championships yesterday after breaking her hand during a training session. She was part of the team who won gold in the 4x100m freestyle on Sunday.
The world meet was Jack's first major international competition in three years after receiving a four-year doping ban, which was later reduced to two years.
AGENCE FRANCE-PRESSE, REUTERS