In Gee Chun's modest goal for her first U.S. Women's Open was to enjoy every new experience.

Boy, did she enjoy herself.

The 20-year-old South Korean stormed from behind, posting birdies on four of the last seven holes to rally for an unlikely one-stroke victory Sunday.

Chun shot a 4-under-par 66 in the final round and finished at 8 under, becoming the first player to win her U.S. Open debut since Birdie Kim in 2005.

When Chun began lengthening her lead, she did it with a smile.

"That's just her makeup and character," Chun's caddie, Dean Herden, said. "She's got a good upbringing and good parents. Coming from a not-well-to-do family, they really trusted in In Gee and her game. They had no money, and she wanted to be a pro golfer, so Mom and Dad stuck with her. It's kind of one of those Cinderella stories."

Third-round leader Amy Yang struggled in the middle of her round and then pulled within one by going eagle-birdie at Nos. 16 and 17. But she bogeyed the 18th and fell a stroke short.

Playing in the final group on the last day of the championship for the third time in four years, Yang squandered a three-stroke lead and settled for a 1-over 71 and second at 273.

Elsewhere

• Rickie Fowler shot a 2-under 68 to earn his first career victory on European soil, defeating Matt Kuchar and Raphael Jacquelin by one shot at the Scottish Open. Fowler's four-round total was 12-under 268.

• Iowa native Jerry Smith shot a 2-under 70 to win the Encompass Championship in Glenview, Ill., for his first title on the Champions Tour. Smith finished at 16-under 200, setting a tournament record.

• Martin Piller completed a wire-to-wire victory in the Albertsons Boise Open for his fourth Web.com Tour title. Piller shot a 4-under 67 for a 28-under 256 total, the second-lowest 72-hole score in tour history.