Jutanugarn lost a seven-shot lead on the back nine before prevailing on the fourth hole of a playoff to win at Shoal Creek on Sunday for her second major championship.
Golf got class-bully mean, Hyo-Joo Kim put on an impressive show and Jutanugarn, no stranger to trouble down the stretch of a major championship, went from invincible to vulnerable.
Both players made par on the third play-off hole, before 2016 Women's British Open victor Jutanugarn saved par to win the title after a deft bunker shot on the 18th.
Anyone who watched surely enjoyed the affair, and they may also have been clued into a specific visual: Jutanugarn applauding successful shots made by Kim during their one-on-one playoff.
Victorian Su Oh was rock solid in shooting 68 to be just four strokes behind Smith. Smith, who is seeking her first LPGA career title, had the luxury of sleeping in Saturday morning because she finished her second round on Friday. She blew a two-shot lead with three holes to go at the ANA Inspiration in 2016, bogeying the final three holes to lose to Lydia Ko.
"I think I'm going to sleep pretty well", Jutanugarn said.
"I'm not really thinking about my position but I'm really happy about my game right now", she said.
She then posted seven straight pars, taking over the lead when Smith stumbled to back-to-back birdies on Nos. eight and nine holes. She realized she wasn't ready to win at the time. "It did not really enter my mind that I was going to come that close".
She did well to hole from eight feet to salvage a bogey and then stripe a confident long-iron down the centre of the fairway at the last just as Kim nailed a tricky six-footer for par to cap a bogey-free 67.
Having been way ahead following an imperious display, a treble-bogey seven on the 10th dramatically shifted the dynamic of the occasion, before bogeys on the two closing holes saw the 22-year-old Thai golfer slip into extra holes with Kim of South Korea, who herself had shot a metronomic 67 on Sunday.
"It's really tough for me because, you know, I didn't have good finish the last two holes".
Defending champion Park Sung-hyun missed the halfway cut with rounds of 76-77, and world number two Feng Shanshan of China also exited early after rounds of 78-74. "Not because I want them to play golf, but because I want them to have a good life", she told Golfweek.
University of Alabama sophomore Kristen Gillman, who ended Thursday's first round in a tie for seventh after an opening 2-under round of 70, did not get to complete her second round due to inclement weather, far from it in fact. "After that I kinda played a little bit scared", she said.