Katie Ledecky edged Australian arch-rival Ariarne Titmus on Sunday to be quickest in the 400m freestyle heats.

The American great kick started a gruelling schedule, which will also see her tackle the 200m, 800m and 1500m freestyle, by touching in 4mins 00.45secs. Titmus cruised through the next heat in 4:01.66, with both keeping plenty in the tank for Monday’s final.