BETHESDA, MD. • In Gee Chun was an upbeat, smiling presence throughout the Women’s PGA Championship — easy enough when you shoot 64 in the first round and lead comfortably for much of the tournament.

In the final round, all of her positive thinking was put to the test.

“Golf is never easy,” the 27-year-old South Korean said.

Chun won her third major championship, playing her best in the first round on a wet day and then persevering through a steamy weekend at Congressional. On Sunday, she quickly lost what was left of a once-sizeable lead, then rallied to win by one when Lexi Thompson’s putting faltered down the stretch.

Chun shot a 3-over 75 on each of the last two days of the tournament. She finished at 5-under 283, barely enough to beat out Thompson (73) and Minjee Lee (70) by a stroke.

“Before start today my coach told me, ‘In Gee, if you enjoy your game, this trophy is yours,’” Chun said. “Sometimes it’s really hard to keep smiling when my game, I mean, going not good, but I think I hung in there. So I’m so proud now.”

After leading by six at the tournament’s midway point, Chun lost a threeshot advantage in the first three holes of the final round. Thompson was two strokes ahead of Chun after the front nine, but Thompson’s putting problems were just beginning.

The 27-year-old Floridian botched a par putt from a couple feet on No. 14, but a birdie on 15 restored her lead to two. Then she bogeyed the par-5 16th while Chun made birdie, leaving the two players tied with two holes remaining.

Thompson, who declined a postround news conference, three-putted for bogey on 17. After an impressive approach from the rough on 18, her birdie putt wasn’t hit firmly enough.

Chun’s approach on the par-4 18th bounced past the hole and just off the back of the green, but she putted to within about 5 feet and sank her par attempt for the win.

It was Chun’s first victory anywhere in the world since 2018 and only her second in the United States — her first was the 2015 U.S. Open. She won her second major the following year at the Evian Championship in France.

Now, Chun is the third player from South Korea to win at least three majors, trailing Inbee Park (seven) and Se Ri Pak (five).

Chun led by seven strokes after finishing her 8-under 64 in wet conditions Thursday. The lead was down to five at the end of that day — still equaling the largest 18-hole advantage in the history of women’s majors.

That impressive beginning gave her some room for error — and also set her up for a potentially grueling weekend of high-pressure golf. She was still six strokes ahead entering Saturday, but the lead was down to three after three rounds.

“The first day, she was really excited because of the 64,” caddie Dean Herden said. “It’s hard to calm down after a 64 because you’re pumped.”

Thompson hasn’t won an LPGA Tour event since 2019, and her lone major victory came as a teenager at Mission Hills in the California desert in 2014.