The 21-year-old rookie, who eventually won by two strokes, went into the final day five shots ahead of the field and was blissfully unaware of her rival tearing up the course ahead of her.
Ko, who has won 15 LPGA Tour events, equaled the course record set by Lorena Ochoa in 2016 by hitting a masterful 10-under 62 on the final day but it wasn’t enough to overtake the eventual winner.
“Didn’t look at the leaderboard at all today,” Tavatanakit said after celebrating her win by honoring tradition and jumping into the pool.
“I saw her [Ko’s] name up there, but I didn’t look at it. I wanted to play my own game, which I did, and did a really good job of that today.”
Ranked 103rd in the world, Tavatanakit is the first rookie champion since Juli Inkster in 1984 and says it’s been a “crazy” ride from her days in the amateur ranks.
“It’s a dream come true,” Tavatanakit said. “Every time I play here, I remember exactly I was on this green receiving my low amateur award and I saw they were jumping and I took a Snapchat and the caption was, ‘One day.'”
Ko had recorded seven birdies and an eagle on the first 11 holes in an astonishing final round before falling agonizingly short. She also set a new course record by hitting 29 after the first nine holes.
The 23-year-old, who became world No. 1 when she was just 17, has been winless since April 2018 but will look to take confidence from her performance in California.
“I was actually thinking in my head, ‘I wonder if on the coverage they are going to be like, ‘Oh, Lydia Ko is back,'” she said after finishing runner-up.
“I hope it’s not the sense that I’m back to a position where I was or where I could be. I just want to be the best version of myself right now.”
The 50th edition of the tournament, held at Mission Hills, was more subdued than normal with fans still absent amid the pandemic.