Kazan: Teenage triple world-record holder Katie Ledecky of the United States retained her 400m freestyle title at the world swimming championships on Sunday to continue her dominance of the distance events.
Ledecky`s victory gave the United States their 100th gold medal in women`s events at all world aquatic championships.
The 18-year-old, who holds the world records over 400m, 800 and 1500m, led by two body lengths at the halfway stage and won gold in three minutes, 59.13 seconds to set a new championship record.
Sharon van Rouwendaal of the Netherlands claimed silver at 3.89 secs back with Australia`s Jessica Ashwood taking bronze at 4.21.
"This gets the momentum going and I couldn`t be happier," beamed Ledecky, who has only just graduated from high school.
She scooped the fifth world title of her career with a commanding display and she admitted she was disappointed not to break her own world record, having come within a second of it.
"I think it`s a very competitive event and I could feel the other girls racing really hard so that gets me going. It was a fast race," she said.
"When I touched the wall, I kind of felt that I had it (broken her world record), so it took me a second to realise that, but at the same time I can`t complain about another world championship medal.
"This gives me a lot of confidence to do well the rest of the week. It gets me excited to do well."
Having won the 400, 800 and 1500m freestyle Olympic titles at London 2012 while just 15 years old, Ledecky then completed the same set at the 2013 world championships when she ended up winning four gold medals including the 4x200m freestyle relay title.
She set world records over the 800m and 1500m freestyle in Barcelona two years go, then bettered both last year and also set a new record in the 400m at the Pan-Pacific Games last August.