Titmus knew Ledecky was the benchmark yet the young Aussie Ariane Titmus pushed the Olympic champ all the way in the 800m free final overnite. The Tassie born 17 year old set a new national record of 8.17.07 and has set her sites on taking time away from Ledecky leading into the next Olympics. Titmus rated her record-breaking silver at the Pan Pacs as a "breakthrough" ahead of Tokyo 2020. Ledecky set a championship record of 8:09.13 to claim the meet's first gold - Cate Campbell sounded a warning to her sprint rivals with a scintilating freestle leg in the final of the inaugural 4 x 100 Mixed Medley. Australia stopped the clock at three minutes, 38.91 seconds - just 0.35 outside the world record, set by the USA in Budapest at last year’s World Championships. Joining Campbell in the victory celebrations were Mitch Larkin (backstroke), Jake Packard (breaststroke), Emma McKeon (butterfly). The Dolphins finished the first nite of competition with 1 Gold, three silver and I bronze medal. The Americans again look the team to beat.