News Katie Ledecky set an Olympic record and nearly broke her own world record in the preliminaries of the 400m freestyle on Sunday (7 August) afternoon, setting herself up as the overwhelming favourite to capture her first gold medal of the Rio 2016 Olympic Games The 19-year-old American, who won the 800m freestyle gold at London 2012, posted a time of three minutes 58 71 seconds, actually backing off a bit on the closing lap to conserve energy for the final on Sunday night She just missed her mark of 3:58 37 set in 2014 No one is even close to Ledecky, who will essentially be racing the clock in the final The next-fastest qualifier was Britain's Jazz Carlin, who was more than four seconds behind American Leah Smith posted the third-fastest time in the preliminaries Ledecky, who will race in the 400m freestyle final at 11pm (Rio time) on Sunday, was part of the US team that took silver in the 4x100m freestyle relay on Saturday night, when they were defeated by an Australia team that broke the world record New era for USA swimming as young stars join Phelps, Ledecky and Co for Rio 2016