LA JOLLA (California) (AFP) - Na Yeon Choi of South Korea surrendered a seven-shot lead but steadied to post a one-under 71 that gave her a one-shot victory in the LPGA Samsung World Championship on Sunday. Choi claimed her first LPGA Tour title with a 16-under total of 272, but it came down to the very last hole. "I can't believe that I won," said Choi, a four-time winner on the Korean tour. "Throughout the second half I thought I was going to lose it again." Japan's Ai Miyazato carded a 69, lowest round of the day, to finish second on 273. South Korea's Jiyai Shin was third on 277. Choi started the round with a two-shot lead. Two birdies in her first four holes were followed by an eagle at six - where she sank a 10-footer - as she stretched her lead to seven strokes. But she hit a quagmire with three bogeys in a row from the ninth, and she lost the lead at the 14th with a three-putt bogey. Meanwhile, Miyazato was gaining with a steady round that included back to back birdies at seven and eight. "I played really good," said Miyazato, who had taken a share of the lead with a four-foot birdie putt at 16. "I was very patient." Choi, who has been working with a sports psychologist, said she drew on what she'd learned after losing the lead with her bogey at 14. "Mentally I felt I was very weak," Choi said. "I kept telling myself to be positive. I wanted to be positive about everything." Miyazato came to the 18th with the lead, but found the water with her second shot. After taking a drop, Miyazato landed her fourth within 20 feet but couldn't make it to save par. "I knew how I stood situation-wise," said Miyazato, who then had to wait and see what Choi came up with at the last. "I knew it was a challenging shot but I made my decision to go for it and I did." Choi, now sharing the lead, left an eagle attempt at the final hole five feet short, but made the pressure putt for birdie and the victory. "I felt like I had just turned professional today," Choi said of her nerves as she faced her putt to win. "I was so nervous. "It was easy, now I look back at it," Choi said. "But it was really difficult when I was doing it."