Sarah Sjostrom fails to qualify for the final of the 100m breaststroke backstroke in Rome . The defending champion and world record holder only ninth fastest in semifinal . Teenager Sarah Sjostrom sets third 56.06 m butterfly world record in under 52 seconds .
Aaron Peirsol fails to qualify for the final of the 100 meters backstroke in Rome . The defending champion and world record holder only ninth fastest in semifinal . Teenager Sarah Sjostrom sets second 100m butterfly world record in 24 hours .