Sarah Kemp laid down the early challenge and Su Oh threatened to make a late charge, but both came up just short as France's Celine Boutier hung tough on Sunday to win the women's Vic Open.
Boutier made a crucial birdie on the par-4 15th hole and showed nerves of steel to claim a two-shot victory in the $1.5 million tournament at 13th Beach.
"I've been working really hard for the last two years," said the 25-year-old Boutier.
"I'm just so happy that I was able to get my first win on the LPGA Tour today.
"I'm very happy with the way I handled myself.
"I was kind of struggling a little bit in the beginning but I just held on and kept fighting to the end."
Boutier carded a final round of level-par 72 to finish on eight-under 281, while Australian duo Kemp (65) and Oh (74) and England's Charlotte Thomas (69) tied for second on 283.
After just making the third-round cut, Kemp teed off on Sunday morning in the second group.
She began her round inauspiciously with a double-bogey before turning things around in dramatic fashion with nine birdies, including five in succession beginning at the fourth hole.
But believing she was still well out of contention, Kemp left the course to enjoy a "big fat Mexican wrap" and a celebratory drink.
Then the late starters began going backwards and it looked for a while as though her total of 283 might be good enough for an unlikely spot in a playoff.
"But once Celine hit her tee shot on 18, I got another drink," Kemp said.
"She had been putting so well; she's a good player; she's won before.
"I didn't expect to be in this situation.
"I made the cut on the number and everything after that was a bonus."
For Oh, it was a fifth top-six finish in the past six editions of the Vic Open, although she was yet to convert any of them into a win.
Playing in the final group alongside overnight leader Kim Kaufman and Boutier, the 22-year-old Oh began sluggishly before threatening to make a move in the closing holes.
The key moment came when her chip for eagle on the 15th grazed the pin but stayed out.
"I hit a good chip, but Celine hit a great putt, so I think that was sort of the deal," she said.
"Even on 16, I hit a good putt and it just didn't go in."
Australian Associated Press