American teenager Katie Ledecky broke a second world record in less than 24 hours when she bettered her own mark for the women's 1500m freestyle at the Pan Pacific championships in Australia on Sunday.
The 17-year-old hacked almost six seconds off the previous world record, which she set in Texas in June, when she charged through the 30-lap event in 15 minutes, 28.36 seconds.
Ledecky also broke her 400m world record on Saturday and came within a whisker of eclipsing her 800m world best on Thursday.
She has won five gold medals at the Pan Pacs, being held at Australia's Gold Coast.