LOS ANGELESP - American teenager Katie Ledecky has sliced 2.86 seconds off her 800m freestyle world record, clocking 8m11.00s at a meet in Texas for her second world record in four days.
The 17-year-old Ledecky improved on her own previous 800m free world record of 8:13.86 set at the world championships in Barcelona in August of last year.
On Thursday night, Ledecky had shattered her previous record in the 1500m free with a time of 15:34.23, improving on the mark of 15:36.53 she had set in Barcelona.
Ledecky is the Olympic champion in the 800m free. The women's 1500m free isn't contested in the Olympics, although it is a world championships event for both men and women.
Ledecky is in strong form with the US Championships in Irvine, California, looming in August.
Those championships are a selection meeting for the Pan Pacific Championships in Australia later that month, as well as the 2015 world championships in Russia.
Meanwhile Olympic superstar Michael Phelps, swimming his first 200m medley race since the 2012 London Olympics, has cruised into the final at the Santa Clara Grand Prix meeting.
Phelps, whose 22 Olympic medals include an astonishing 18 golds, won his heat comfortably on Sunday in a time of 2min 0.89sec - 1.2sec in front of Max Williamson.
Phelps led a sweep by North Baltimore Aquatic Club swimmers of the top three qualifying spots.
Clubmate Chase Kalisz won his heat in the morning's second-quickest time of 2:01.69 and Conor Dwyer won his heat in the third-fastest time of 2:02.05.