It was a different story as she made her victory speech, tears flowing freely as she thanked New Zealand Golf for supporting her journey to the top of world golf.
"New Zealand Golf, there's no bigger word than thank you ... oh, I'm going to cry," she said. "I want to thank you guys for always having hope in me. With my South Korean background, there was always doubt: is she going back to Korea? Is she going to stay? But you stuck with me and made it easier for me and I wouldn't be here without you guys - you are a huge part of my career."
Further tears flowed as she added: "And that's why I miss Patsy even more," referring to the late Patsy Hankins, a long-serving New Zealand Golf administrator and mentor to Ko, who passed away in October.
Ko was back to her joking self at her press conference, saying she was prepared to blame aftershocks for her raft of missed putts in the final round.
"I'll say it wasn't me, it was the ground moving that made it go away from the hole."
In the end, that might have been a handy excuse as the world No 1 struggled with her putter throughout the day and missed numerous chances to build a more substantial lead. She made three birdies, offset by a three-putt bogey on the par-5 fifth, and never broke from the pack.
At one stage, she was in a five-way tie for the lead and to an extent relied on her challengers stalling or fading as she rode a two-shot cushion over the closing seven holes, with back to back birdies on the 10th and 11th giving her breathing room. The birdie putt on 11 was the one that kept her frustrations at bay.
"By that time, you're thinking 'the hole is big enough for the ball to fit in it, why is it not going in?' But that was the best stroke I'd put on it all day. Making those two birdies in a row put me in good rhythm."
She shot a final round of two-under par 72 to finish at 10-under and two shots clear of the second-placed trio: South Korean amateur Hye Jin Choi, England's Felicity Johnson and Dane Nanna Moertz Madsen.
It was her third New Zealand Open win, her 11th victory as a professional and her 15th career title.
Leading scores
206: Lydia Ko (NZL) 69 67 70
208: Choi Hye-Jin (KOR) 71 68 69, Nanna Madsen (DEN) 70 68 70, Felicity Johnson (ENG) 70 71 67
209: Justine Dreher (FRA) 67 70 72