American teenager Katie Ledecky broke her own world record for the women's 400 metres freestyle at the Pan Pacific championships on Saturday.

The 17-year-old won the final at Australia's Gold Coast in three minutes, 58.37 seconds, slashing almost half a second off the previous world record she set in California earlier this month.

“It's a good feeling,” Ledecky said in a poolside interview. “I was just racing my best time and trying to swim faster.”

Ledecky also holds the women's world record for 800m and 1,500m freestyle. – Reuters