Japan's gold medal hope Daiya Seto failed to qualify for the men's 400-meter medley final after finishing ninth in the heats.
The 27-year-old Seto, the world champion and top ranked in the event, was the bronze medalist in Rio five years ago and favourite to win gold in Sunday's final before his shock exit.
Australia's Brendon Smith was fastest with a time of 4:09.27 followed by New Zealand’s Lewis Clareburt and American Chase Kalisz.