SAN DIEGO — Na Yeon Choi blew her best chance for the first LPGA Tour win of her career.

Her second chance worked out just fine.

After losing a seven-stroke lead yesterday, the South Korean rallied to shoot 1-under 71 and win the Samsung World Championship on the 18th hole.

"I can't believe that I won," Choi said. "Throughout the second half I thought I was going to lose it again."

Choi finished at 16-under 272 and held off runner-up Ai Miyazato of Japan, who shot a 69, the low round of the day at Torrey Pines.

Choi began the final round with a two-stroke lead, got birdies on two of her first four holes and made a 10-foot eagle putt on the sixth hole to extend her lead to seven strokes.

It looked then as if Choi, who has won four times on the Korean LPGA Tour, would cruise to her first LPGA Tour victory.

But Miyazato, playing in the group in front of Choi and Jiyai Shin of South Korea, birdied Nos. 7 and 8 to cut Choi's lead to five.

Choi missed a 2-foot putt on the ninth hole for a bogey, cutting the lead to four heading into the back nine.

She continued to struggle with two consecutive bogeys, and Miyazato tied Choi at 16-under with a 4-foot birdie putt on No. 16. Miyazato took the lead shortly after, when Choi three-putted for bogey on No. 14.

On the 18th hole, it was Miyazato's turn to make a mistake. With 203 yards remaining for her second shot, her 5-wood approach hit the bank in front of the green and rolled into the water. She dropped in front of the pond but could not get up and down for par.

Choi's second shot on the 18th reached the front left of the green and her third shot came to rest 5 feet below the pin. Choi, who had missed several putts of equal or less distance, converted the birdie for the victory.

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