China's Shi Jinglin, Lu Ying and Fu Yuanhui (L-R) react after winning the women's 4x100m medley relay final at the Aquatics World Championships in Kazan, Russia, August 9, 2015. [Photo/Agencies]

China's backstroke specialist Fu Yuanhui led the Chinese women to a surprise gold medal at the 4x100m medley relay, the last event of the world swimming championships on Sunday.

"I was so tired after eight days of competition," said Fu, 50m backstroke winner on Thursday. "I swam for my life."

China clocked 3:54.41 to claim gold with Sweden winning silver at 0.83 seconds and Australia taking bronze at 1.15 back. Defending champions the United States finished fourth at 2.35.

The United States pocketed the men's 4x100m medley relay gold with 3:29.93. Australia trailed in 3:30.08 and France took third in 3:30.50.

Australia's Bronte Campbell, winner of the women's 100m freestyle on Saturday, breezed to win the 50m free. She clocked 24.12 to finish ahead of Dutchwoman Ranomi Kromowidjojo who timed 24.22 and Swede Sarah Sjostrom, 24.31. Campbell's sister Cate finished fourth in 24.36.

Frenchman Camille Lacourt timed 24.23 to win the 50m back with Matt Grevers of United States finishing second at 0.38 and Ben Trekkers of Australia third at 0.46.

Sweden's Jennie Johansson was the surprising winner of the women's 50m breaststroke at 30.05. Jamaica's Alia Atkinson finished second in 30.11. Russian Yuliya Efimova, winner of the 100m breast in Kazan, timed 30.13 to take third. World record holder Ruta Meilutyte of Lithuania only took fourth in 30.14.

In a final without out-of-form Olympic champion Ye Shiwen, Hungary's Katinka Hosszu dominated the women's 400m medley in 4:30.39, while in the men's 400m medley, Japan's Seto Daiya claimed victory in 4:08.50.