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For a good part of her back nine Sunday, Na Yeon Choi's chances of winning the U.S. Women's Open were hanging in the balance.

Or, more accurately, they followed her ball as it flew into a hazard next to the 10th fairway, got stranded in high grass on a hill next to the 12th green, and bounced along the rocks just in front of the water at the 13th.

But thanks to a handful of key shots under pressure, a little luck and a lot of nerve down the stretch, Choi recovered to run away with her first major title.

The 24-year-old shot a 1-over 73 at Blackwolf Run to finish at 7-under-par 281, four strokes in front of Amy Yang.

"I think I couldn't believe this right now," Choi said. "Maybe tomorrow in Korea I can feel something."

Choi had fired a 65 on Saturday to build a 6-stroke advantage heading into the final round, and she needed the big cushion. Her lead over Yang was down to two strokes at one point, but Choi extended it thanks to two late birdies.

Yang shot a 1-under 71 to end at minus-3, and was the only other player to finish below par. Sandra Gal (74) took third at 1-over 289.

Choi had previously won five LPGA Tour titles, but hadn't pulled out a major victory despite being consistently in the hunt. Prior to Sunday, the Korean finished inside the top 10 at eight major tournaments, including a tie for second at the 2010 U.S. Women's Open.

And halfway through her round, she appeared to be on the way to a dominating win, still sitting at minus-8 after carding a bogey and birdie on her front nine.

But then Choi stepped to tee No. 10 and ripped her shot into the hazard.

"I think my swing was a little quick, so my ball started a little bit left," Choi said. "And then the wind [came] from off right-to-left, so the ball moved to the left. And then my ball carry over the hazard left side."

According to an explanation on the USGA's site, the ball "was hit into the lateral water hazard down the left side." It said players, marshals, referees and available television coverage were used to determine if the ball last crossed the hazard margin by the fairway, or close to the teeing ground.

Because they determined the ball last crossed the margin near the teeing ground, Choi headed back to the box for another try.

She eventually carded a triple-bogey 8 at the par-5 to sink to 5-under, and was just two strokes in front of Yang, who had birdied the ninth to reach 3- under.

"That moment maybe I thought I might screw up today, but I thought I needed to fix that," Choi said. "I can do it."

After that hole, she said she decided to talk with her caddie about anything other than golf. Having moved past the mistake at the 10th, Choi rebounded nicely at the par-4 11th, where she hit her second close to the hole to set up a birdie.

However, she was back in a precarious position at the next hole, with the ball sitting in some tall brush on a steep slope next to the green. But she chipped onto the green and saved par.

Luck came into play at the par-3 13th, where a water feature runs parallel to the long, narrow green. It featured a tough pin placement Sunday, when the hole was at the far end of the green. The hole also has a tough tee location, forcing players to hit at a slight diagonal shot over the water and to the green. The ball can't be hit directly over the lake, like it was an obstacle to drive past. It's a little like trying to drive the ball through a tunnel.

So players can either challenge the water or play it safe and leave themselves with long putts.

Choi opted to go for the pin, but her shot was a tad short, and it bounced along the rocks at the edge of the green -- feet away from the water -- before settling at the far end, just off the surface. She got up and down for another par.

From there, Choi's lead only grew.

Yang bogeyed the 14th and birdied the 15th to stay at minus-3.

Meanwhile, Choi got a nice bounce at the par-4 15th to keep the ball near the fairway. She birdied that hole to get back to minus-7, then birdied the next to push her lead to five.

Because Yang parred out, Choi just needed to avoid big mistakes to secure her victory. She parred 16 and 17, then missed a par putt at the last. But by that point, her lead was safe.

Choi knocked in the easy bogey putt to clinch the title at the same course where Se Ri Pak won the 1998 U.S. Women's Open. Pak's success led to an influx of Korean players on the LPGA Tour, and Choi is just the latest evidence of that. Her win Sunday is the fourth U.S. Women's Open victory by a Korean-born player in the last five years.

"I was only [10] years old, and like when I was watching TV, my dream was like I just want to be there," Choi said about wanting to be an LPGA player. "And 14 years later I'm here right now, and I made it. My dreams come true. It's an amazing day today, and like I really appreciate what Se Ri did and all the Korean players, they did. It's really no way I can be here without them."

Pak was there at the 18th green Sunday, waiting with a bottle of champagne and smiling. And when the final putt went in, the Hall of Famer and a host of others rushed onto the green, dousing Choi with champagne and congratulating the new champion with a hug.

NOTES: Choi pocketed $585,000 for the victory...Pak (71) finished in a tie for ninth, at plus-4...Paula Creamer, the 2010 U.S. Women's Open champion, was the top-placing player from the United States. She shot a 2-over 74 and shared seventh with Mika Miyazato (76) at 3-over...World No. 1 Yani Tseng carded a 6- over 78 and finished in a tie for 50th at plus-14...So Yeon Ryu (74), the 2011 champion, tied for 14th at 5-over...The LPGA Tour is off until July 26, when the Evian Masters begins. Ai Miyazato won last year.