'Everything was kind of easy,' Jang said after tying the second-lowest round of her career. 'I wanted to hit a spot on the fairway, I did. I wanted to hit a spot on the green, I did.'
Jang opened with a 4-foot birdie putt on the first hole at Blackhawk Country Club, and it didn't get much harder than that. None of her eight birdie putts were longer than 6 feet.
But she owed more to the success of her irons and short chipping game than her putting.
'The greens are kind of small,' Jang said. 'When you hit them, you are going to have a short putt.'
The 64 established a new course record -- beating the old record of 65 -- although the LPGA didn't know who the previous record holder was. It came on a day when only 40 players in a field of 131 broke par.
Karrie Webb and Lorie Kane shared second place at 5-under 67, one shot ahead of a group that includes Lorena Ochoa, Jill McGill and Candie Kung at 4-under.
Tour money leader Ochoa has been battling for the top spot with Webb all year. She would be tied for second place alongside Webb if not for a bogey at the 17th, her only bogey of the round.
'I'm trying to take it one week at a time,' Ochoa said. 'This is an important week for me. I believe I can win the tournament, so I need to keep playing good for three more days.'
Annika Sorenstam, the 1997 champion, opened with a 2-under 70 and is tied for 19th place. Her up-and-down round included three bogeys -- including two on her first three holes -- and five birdies.
'Looking at my scorecard and going through it makes me tired,' Sorenstam said. 'A lot of bogeys, a lot of birdies, a lot of up and downs.
'Obviously, I'm happy to come in at two-under when you get off to a start like the way I did. I fought back pretty well, I thought. But I'd like to see it get better from here.'
It doesn't get much better for Jang, who also had a 64 in the final round of the ShopRite LPGA Classic in June. She shot her career-best round at the 2004 Longs Drugs Challenge, where she closed with a 62 to finish tied for fifth.
Thursday, she followed her birdie at the first with 1-foot birdie putts at Nos. 5 and 9 to make the turn at 3 under.
Jang continued attacking pins on the back nine, knocking approach shots within 2 feet, 5 feet and 2 feet again at the 11th, 13th and 15th holes. She closed her round with back-to-back birdies at 17 and 18, both from 5 feet.
'I had good second shots today,' said Jang, a two-time winner on the LPGA Tour, 'so putting wasn't really hard.'