Celine Boutier of France claimed a two-stroke victory in the LPGA's Vic Open on Sunday while Scotland's David Law made eagle on the par-5 18th to win the men's title by a stroke over Australians Brad Kennedy and Wade Ormsby.
That 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 on his 264th attempt.
Ormsby, playing the hole behind, crumbled with a double-bogey on the par-three 17th to give Law the club-house lead and missed a long eagle putt on the last that would have forced a playoff.
It has been cosanctioned this year by the European Tour and US-based LPGA Tour for the first time.
South Africa's Justin Harding finished fourth on 16 under with Scotland's David Drysdale and Australians Jason Scrivener and David Bransdon a shot further back.
"It's massive. It's not something I expected".
"I'm so happy with how I handled myself today". I'll go home, reflect a little bit on things and reassess.
"Walking to the tenth I hit the reset button and tried to keep calm", said Law, who called a penalty on himself for a moving ball on the ninth which resulted in a bogey. I just kept grinding, really, that's all we can do in weather like that.
The tournament is co-sanctioned by the European Tour and LPGA and features men and women playing on the same courses at the same time, for equal prize money.
"We said we were going to try to finish three-two-four in the hope that we could get a top-three finish".
"We stood on the tee and we said we need to make eagle", Law said at the trophy presentation after claiming a A$1.5 million ($1.06 million) winner's cheque.
A 30-foot birdie at the 15th hole proved decisive for Boutier, pulling her two strokes clear and allowing her the relative luxury of making par for the win on eight-under-par 281 total. "We make eagle, we post at 18 under, you never know what can happen". The Frenchwoman finished on eight under to hold off local favourites Sarah Kemp and Su Oh, as well as England's Charlotte Thomas.