Pettersen and Lee, a local favorite, each shot three-under-par 69 and own a two-stroke lead after the first day of the tournament. Jeong Jang, Moon Hyun-hee Moon, Kim Joo-mi and Catriona Matthew were all tied for third at one-under 71. World No. 1 Lorena Ochoa was among six players tied for seventh at even-par 72.
Pettersen was two-over at after nine holes, with a double-bogey on No. 8 and a bogey on 9 pushing her score up. But she played the back nine in five-under, starting with birdies at 10 and 11 that got her back to even and ending with birdies at 17 and 18 that gave her a share of the lead.
Lee, who played the back nine first on Friday, also birdied 17 and 18 and played solidly on the front nine, posting eight pars and a birdie at No. 3 to tie for first.