McIntosh, who won three gold medals a year ago at the Paris Olympics, holds the world record in the 400 free — 3:54.18. She will face off again with Ledecky in the 800 free later in the meet, probably the most anticipated race in Singapore.

In the first of two anticipated showdowns at world championships, the Canadian phenom McIntosh was dominant against the American Ledecky.

Huske, the Olympic 100m fly gold medalist, withdrew from the event to prioritize the 4x100m free relay, according to USA Swimming. She can still race the 50m and 100m frees later in the meet, plus more relays.