Starting from the 6th hole, Hedwall registered 10 straight pars and then the first of five birdies at the 16th before producing the highlight of the day as she aced the 17th from 162 yards.

"I heard how it hit the pin and then I thought it came off because something white flew off the flag stick," Hedwall told

"I thought my ball was in the bunker. I walked up and saw a ball in the bunker and remarked there it is but my Pro-Am partner said that it was his ball.

"So I walked up to the hole to double check and it was there. I realised just after the hole-in-one that I'd won a watch, which is cool."

The bogey-free round left her seven under par (65), while Germany's Laura Fuenfstueck and France's Celine Boutier are both at five under.

New Zealand's Lydia Ko is at four under, while a group tied in fifth place at three under includes Spanish defending champion Nuria Iturrioz, England's Meghan MacLaren and Scotland's Alison Muirhead.

Stephanie Kyriacou is the best-place Australian, tied for 12th at one-under.

Compatriot Minjee Lee carded an even-par 72 while Whitney Hillier shot a five-over 77.