Miyazato, six strokes behind Pettersen after the third round, was 6 under in a six-hole stretch midway through the round, then birdied three of the last six holes to match the tournament record of 21 under set by Pettersen in October 2007.
Pettersen finished with a 70 Siam Country Club’s Old Course. She had a chance to force a playoff on the par-5 18th, but missed a 23-foot eagle try.
The 24-year-old Miyazato earned $195,000 for her second LPGA Tour title. She also won the Evian Masters last year in France and has 15 victories on the Japanese tour.
“I didn’t think of winning. I was just focused on my game and tried to do my best in the final round,” Miyazato said. “It was my lucky day as no matter what I did was right. This victory is a good start of the season for me.”
Taiwan’s Yani Tseng (69) was third, six strokes back at 15 under. Karrie Webb (67) and Cristie Kerr (70) followed at 13 under, and Laura Davies 65), Maria Hjorth (71), Momoko Ueda (72) and Song-Hee Kim (73) were 12 under.
Top-ranked Lorena Ochoa, the winner last year, had a 72 to tie for 18th at 6 under, while Michelle Wie closed with a 69 to tie for 22nd at 5 under.
“Wish I could have made a few more putts. Hopefully I’ll play better next week,” said Wie, set to play next week in the HSBC Women’s Champions in Singapore
Miyazato began her big mid-round run with a birdie on the par-4 sixth, then eagled the par-5 seventh and added birdies on Nos. 9-11 to cut Pettersen’s lead to a stroke.
Pettersen dropped a stroke on the par-4 ninth with her first bogey of the tournament, but birdied the par-5 10th for the fourth straight day to push her advantage back to two strokes. Miyazato quickly countered, birdieing the 13th to again pull within one, and making another birdie on 15 to tie Pettersen at 20 under.
Pettersen fell back with a bogey on 16, then settled for a birdie on 18 after missing her eagle try. In her 2007 victory, Pettersen beat Davies with an eagle on 18 after blowing a seven-stroke lead in the final round.
