Hong Kong's Siobhan Haughey took bronze as China's Tang Qianting capitalised on the absence of US world record holder Lilly King and a slew of other big names to win the 100 metres breaststroke title at the World Championships in Doha on Tuesday.

Tang, 19, took the title in 1:05.27 as Haughey faded in the final fifty metres, with Dutchwoman Tes Schouten coming through for silver.

"I entered this for fun," said freestyle specialist Haughey, who earlier qualified second for Wednesday's 200m freestyle final.

Elsewhere, South Korea celebrated a second gold medal at the World Championships as Hwang Sun-woo claimed the men's 200 metres freestyle title but champion Ahmed Hafnaoui crashed out of the 800m in another shocking setback for the Tunisian.

Two days after team mate Kim Woo-min took a surprise gold in the men's 400m freestyle, Hwang stormed to victory in one minute and 44.75 seconds at the Aspire Dome pool in Doha to improve upon the bronze he won at Fukuoka last July.

"Clearly, we have great relationships within the team," the 20-year-old told reporters.

Having bombed out of the 400m freestyle preliminaries as favourite on Sunday, Tunisian Hafnaoui exited the 800, qualifying 18th fastest.

His time of 7:51.72 was more than 14 seconds off his championship-winning swim at Fukuoka last July.

Italian distance swimmer Simona Quadarella has no such concerns and confirmed she will be the chief threat to American great Katie Ledecky in the 1,500m freestyle at Paris.

With Ledecky absent, Quadarella romped to her second world title, and first since 2019, in 15:46.99, nearly 10 seconds ahead of China's Li Bingjie, also the 400m silver medallist.

In a depleted women's 100 metres backstroke field, Claire Curzan stormed to victory for the United States in a personal best 58.29, adding to her 100m butterfly silver.

Her U.S. team mate Hunter Armstrong took the men's 100m backstroke gold in 52.68 seconds, pipping Spain's Hugo Gonzalez by 0.02 seconds. (Reuters)