Swimming: Distance stars Sun and Ledecky both retain 400m freestyle world titles

KAZAN, Russia (AFP) - The world's dominant male and female distance swimmers both successfully defended their 400m freestyle titles at the world swimming championships on Sunday.

China's superstar Sun Yang won the men's gold as he opened his world swimming championship campaign in style. And triple world-record holder Katie Ledecky of the United States retained her women's title.

The Olympic champion Sun clocked 3min 42.58sec, with Britain's James Guy taking silver at 1.17sec back and Canada's Ryan Cochrane won bronze at 2.01 sec, as the first medals of these championships were decided.

This is the first of four individual events 23-year-old Sun, the world 1,500m freestyle record holder, will race in, as well as the 200m, 800m and the 1,500m distance.

He courted controversy in 2014 after it emerged he had quietly served a three-month doping ban from the Chinese swimming authorities for taking a banned stimulant.

Having won the 400m and 1,500m freestyle Olympic titles at the 2012 London Olympic Games, Sun continued his domination of the endurance events by winning the 400m, 800m and 1,500m world titles in Barcelona two years ago.

The 18-year-old Ledecky, who holds the world records over 400m, 800 and 1,500m, led by two body lengths at the halfway stage and won gold in 3:59.13 to set a new championship record.

Sharon van Rouwendaal of the Netherlands claimed silver at 3.89sec back with Australia's Jessica Ashwood taking bronze at 4.21.