The pioneering tournament, south of Melbourne, is the only one in the world with male and female fields, playing in alternate groups on the same course and for equal prize money.
It has been co-sanctioned this year by the European Tour and US LPGA Tour for the first time.
After some low scoring during the first two days, the players were met with brutal winds and a fierce band of early rain Saturday, making life difficult around the 13th Beach Links course.
England's Callum Shinkwin and South Africa's Justin Harding were undeterred, shooting impressive 66s, but the round of the day went to Australia's Matt Stieger who overcame the elements with a 65.
It left him tied for second with Shinkwin -- two behind Australia's 38-year-old Ormsby, who carded a 70 as he aims to add to his first European Tour success at last season's Hong Kong Open, which he achieved at 264th attempt.
"We got hammered with the rain for about three or four holes there, so it was really good to get through that stretch," said Asian Tour regular Stieger after sinking seven birdies to stay in the hunt.
"No bogeys today, which is really nice. Just stuck to my game plan out there."
Overnight leaders Jason Scrivener and Nick Flanagan didn't fare as well, both struggling to 76s, leaving them five adrift.
Kaufman, who is targeting her first LPGA Tour win, had a two-shot lead overnight but by the sixth hole she had been reeled in by Japan's Haru Nomura.
The American then holed a difficult birdie from the front bunker at the short par-three seventh -- known locally as 'the postage stamp' after the famous par-three at Royal Troon in Scotland -- to regain control.
She holed further birdies at the ninth and 13th before a double bogey at the 14th tarnished her scorecard.
After a solid start Nomura's touch deserted her on the back nine, with three bogeys leaving her three off the pace.
France's Celine Boutier shot a 69 to put herself in contention, two behind Kaufman and alongside Australian Su Oh in second place.