Australian teenager Minna Atherton has been in the United States for 55 seconds in the 100m backstroke, by setting a new shortcourse.
The 19-year-old clocked 54.89sec break the previous mark of 55.03sec set by Hungarian golden girl Katinka Hosszu at the 2014 world championships.
"I'm really happy with that, especially since I just missed it in the relay (earlier in the day)," said Atherton.
"It will be exciting to see what is coming up in the future.
"It's amazing. That's pretty exciting, I'm super happy with that swim.
"I just gave it a red-hot crack."
Fellow Aussie swimmer Maddie Groves heaped praise on Atherton on Twitter.
"Australia we have a new World Record holder in the pool !!! Congratulations young CHAMP
@MinnaAtherton creating history, "Groves wrote." WR & first woman under 55 in the 100m backstroke short course, amazing. "
On its official Twitter account, the International Swimming League called Atherton's achievement "out of this world".
The teenager already has an individual silver medal, picked up in the 100m backstroke in this year's world championships, and another silver medley relay team.