Katie Ledecky is still queen of the 400m freestyle, but now a younger swimmer is closer to Ledecky than any previous rival.
Ledecky won the 400m free at the Pan Pacific Championships in 3:58.50, the sixth-fastest time ever. She was under world-record pace through 250 meters in Tokyo. None of that is a surprise.
Runner-up Ariarne Titmus has been the recent revelation, clocking an Australian record 3:59.66 on Saturday and finishing about a body length behind Ledecky, outsplitting her in the last half of the race. Nobody has been that close to the American in a major 400m final.