San Francisco - World record-holder Katie Ledecky blazed to victory in the women's 1 500m freestyle at the Santa Clara Pro Swim on Thursday in 15:35.65 - the fifth-fastest time in history.
It's also the fifth-fastest time ever by Ledecky herself - who now owns the six fastest swims in the event.
Ledecky hadn't raced a 1 500m freestyle - which is not an Olympic event for women - since setting the world record of 15:25.48 at the 2015 World Championships in Kazan, Russia.
"I wanted to try to put together a good swim. I was maybe a little aggressive on the first 50, but I was able to settle into a pretty good rhythm and pick it up the last 100m," said the American, who was nearly 40 seconds clear of the field.
Chile's Kristel Kobrich was second in 16:12.89.
"I wasn't able to bring in my legs in the middle of the race the way I wanted to, but that's where I am with training right now. I was pretty surprised with the time based on how it felt. It didn't feel as fast as a 15:35, but I'm happy with that," said Ledecky, who won four gold medals at the 2016 Rio Olympics and is now targeting the 2017 World Championships in Budapest in July.