Teen titan turning heads in Kazan

American teenager Katie Ledecky wrote swimming history again at the world championships on Tuesday as three records fell and Australia won backstroke double gold.

Ledecky underlined her status as the star of the Kazan pool by demolishing her own 1,500m freestyle record in Tuesday's final, then qualified for Wednesday's 200m freestyle final less than 30 minutes later.

She has only just graduated from high school, but the 17-year-old Ledecky broke a world record for the ninth time in two years when she shaved 2.23 seconds off her 1,500m personal best to clock 15 min, 25.48 sec.