She edged out Australia’s Mollie O’Callaghan by just one hundredth of a second, touching the wall in 52.79 seconds.
The two Olympians were locked in an epic battle on the first night of competition in Shenzhen, with Haughey ultimately prevailing in the nail-biting finish.
American Kate Douglass took third place with a time of 53.40 seconds.
The tournament is being held at the Shenzhen Universiade Center Natatorium, a venue that holds fond memories for Haughey.
It was there that she enjoyed a successful debut run at last year’s National Games, where she captured four medals – including a gold in the 100-metre freestyle event.
Haughey has a busy schedule ahead: she will also compete in her signature 200-metre freestyle, along with the 50-metre freestyle and the 100-metre breaststroke.
Prize money will be awarded to each event’s top finishers, with gold medallists taking home US$10,000, followed by US$6,000 for silver and US$4,000 for bronze.
Edited by Aaron Tam
