Shiwen Ye has earned a gold medal for China in the women's 400m individual medley with a world record time of 4:28.43.
The 16-year-old lagged behind Hungarian favourite Katinka Hosszu, but powered ahead during the breaststroke length and left her competitors behind.
Elizabeth Beisel of the USA secured silver with a finish time of 4:31.27, while Ye's compatriot Xuanxu Li bagged a bronze.
Early pace-setter Hosszu had to settle with fourth place, and Team GB's medal hope Hannah Miley came in fifth.
China also took the gold in the men's 400m freestyle, with Yang Sun emerging victorious.