After shooting an even-par 72 in her first two rounds, nobody would have predicted what unfolded yesterday and Lee's nine-under total for the week saw her finish one shot ahead of defending champion Lydia Ko.
Ko, who struggled to make enough birdie putts in her final round, was tied for second at eight-under with her playing partners Beth Allen and Anya Alvarez heading into the 18th hole, but none of the trio could make a birdie to force a playoff with Lee.
Allen and Alvarez eventually bogeyed the last as they slipped to a share of third alongside former course record holder Seon Woo Bae, while Ko's par saw her hold on to second.
"I think we all tried to go for it," Ko said. "It didn't end up as that birdie miracle or magic but I think we all played good."
An elated Lee didn't even see Ko's group complete the final hole as she was practising on the putting green in anticipation of a playoff, but her dad, who caddied for her during the tournament, gave her the good news shortly after.
Lee's record-setting effort included seven birdies and an eagle at the par-five second hole, which kickstarted her round. Like Ko, Lee also battled with a stomach bug during the first two days of the tournament and said it was some home cooking that helped put her health right before the final round.
"I'm staying with my host family and my host family friend is Korean and they make kim chi and Korean food and it's better."
Ko said she felt okay during her final round of play, although some stomach pains at the turn didn't help proceedings.
The world No4, who was a hot favourite to become the first back-to-back champion in the tournament's short history, began the day two shots back from Alvarez and it looked like the pressure may get the better of her when she bogeyed the first.
But despite a crowd of about 4000 people following her every shot, the 16-year-old steadied herself and made birdies at two and three as she kept in touch with the leaders.
She gave the crowd hope when she holed a great putt at 17 but when she missed her birdie chance at 18, Lee was left victorious and Ko had to settle for second as she carded a two-under 70 in her final round.
"I was coming like fourth or fifth until the 16th hole and then I kind of came second just by myself. So it also says you're a little short of coming first but it also means that you're close and you can do it next time."
Ko will take this week off before she heads across the Tasman to play in the Australian Open in Melbourne from February 13.
