SHOAL CREEK, Ala. (CNN) – Heading into the back nine at the U.S. Women’s Open with a seven-shot lead, Thailand’s Ariya Jutanugarn briefly appeared in danger of emulating the great Arnold Palmer for all the wrong reasons.

Palmer collapsed in spectacular fashion at the U.S. Open in 1966, surrendering a seemingly unassailable advantage before losing a playoff to eventual champion Billy Casper.

This weekend at the Shoal Creek Golf and Country Club, Jutanugarn did no such thing.

What might have been the most difficult day of the 22-year-old’s career ended with her winning Sunday’s playoff against Hyo-Joo Kim and walking away $900,000 richer with a second major title. She certainly didn’t make it easy for herself.

“On the front nine, I did everything I want to do, but that back got me a lot,” Jutanugarn told reporters after a triple bogey on the 10th kickstarted an almost terminal collapse. “I saw the scoreboard and, on 10, I didn’t feel comfortable to hit a three wood. I was a little bit scared.”

Meanwhile, Kim was closing the gap. Fast. The South Korean, who shot a major record 61 at the 2014 Evian Championship, steadily chipped away at Jutanugarn’s lead, ending the round as the only player with a blemish-free scorecard. The Thai, by contrast, made further bogeys on the 12th, 17th and 18th. A playoff awaited.

A positive mindset was the key to Jutanugarn’s subsequent victory, secured after the fourth playoff hole. “Honestly, I tried to smile,” she said. “I thought if I kept doing that, it was going to make me happy. I tried hard to do that.”

“After you have a seven-shot lead and have to go to a playoff, you kind of have no expectation,” Jatanugarn added. “I got mad a little bit about what happened in my back nine, but I decided I’d just make sure I’d do my best to every shot.”

“Because I felt disappointed already, I didn’t think about the outcome,” Jatanugarn said. “It just felt like a last chance to make myself proud. I just took the shot in front of me.”

Jatanugarn joins Annika Sorenstam, Karrie Webb, Se Ri Pak and Inbee Park as the only players to win both the U.S. Women’s Open and the British Open. Palmer never won a major again after his collapse all those years ago. Jutanugarn, at this rate, appears to be just getting started.

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