BALTIMORE, August 9, 2014 (AFP) - "I hit it really good this year, but I just haven't putted as well," Park said. "Putting like this feels like I'm back to last year, so hopefully I can hole some more putts the next two days."
Park, who won six times in 2013, finished 36 holes at 10-under 132. She earned her 10th career win on the LPGA Tour at the Manulife Financial LPGA Classic in June.
"I had one bogey yesterday, but today I had no mistakes out there. So yeah, I putted really well out there," said Park. "When you're putting really well, it's real easy to score."
Suzann Pettersen fired a seven-under 64 to jump into second place at nine-under 133 at the Blythefield Country Club course.
South Korea's Lee Mi-Rim also shot 64 to take third at minus-eight while Amy Yang (67) is alone in fourth at seven-under 135.
First-round leader Sandra Gal tripped to a one-over 72 during her second round to fall into a share of fifth place at five-under 137. She was joined by Lydia Ko (68), Haru Nomura (67), Line Vedel (69) and Katherine Kirk (70).
Park, who started on the 10th tee, began her round with three consecutive birdies to move to eight under.
She parred the next 10 holes before draining a birdie at the fifth.
The former world number one reached 10-under with another gain at the eighth, and closed her bogey-free round with a par at the ninth to claim the lead.
Pettersen pulled within one of Park with birdies at the 11th and 14th, before a bogey on 16 dropped her back to eight-under. She got that shot back with a birdie at 18.
"It's not like the easiest course if you miss the fairways, but just really tried to played to my strength, hit the fairways, hit greens and made a couple of putts," Pettersen said.
Leading scores on Friday from the second round of the LPGA Meijer Classic (USA unless stated, par-71):
132 - Park In-Bee (KOR) 66-66
133 - Suzann Pettersen (NOR) 69-64
134 - Mirim Lee (KOR) 70-64
135 - Amy Yang (KOR) 68-67
137 - Katherine Kirk (AUS) 67-70, Sandra Gal (GER) 65-72, Haru Nomura (JPN) 70-67, Lydia Ko (NZL) 69-68, Line Vedel (DEN) 68-69
138 - Feng Shan-shan (CHN) 69-69, Gerina Piller 68-70, Azahara Munoz (ESP) 68-70, Giulia Molinaro (ITA) 71-67
139 - Laura Davies (GBR) 71-68, Paula Creamer 69-70, Kris Tamulis 70-69, Alejandra Llaneza (MEX) 70-69, Sydnee Michaels 69-70, Beatriz Recari (ESP) 70-69, Katie Burnett 71-68