KUALA LUMPUR, October 10, 2013 (AFP) - The South Korean has won three of her six Majors this year but has been without a victory since June.
Park, who has never successfully defended a title, won here last year, but trails compatriot Lee Il-Hee, who shot a seven-under 64.
"My irons weren't loose enough. I'm trying to relax a bit more and go for it tomorrow," said the world number one, who had three birdies against two bogeys.
"I'm not a good player in hot weather, but did well last year in Thailand and Malaysia, so I'll keep going," added Park, who finished her round minutes before the weather changed and rain fell at the Kuala Lumpur Golf and Country Club (KLGCC).
"As I said earlier, my goal is to win the Player of the Year award as I didn't get it last year."
Park leads the season's prize-money list with US$2,306,328 and also tops the Player of the Year rankings with 290 points, 86 ahead of Norway's Suzann Pettersen, who carded a 67 here.
Lee, who tied for 16th last year, has a one-stroke lead over Britany Lang after the American bogeyed her final hole. Lee shot a flawless round with birdies on the first, seventh, ninth, 13th, 14th, 15th and 17th.
"The putter was good today. Everything was good," said Lee, who captured her maiden LPGA title in the rain-shortened Pure Silk-Bahamas LPGA Classic in the Bahamas five months ago.
She added her goal coming into the tournament was to shoot three-under on each of the four days of the US$2 million tournament.
Four players - Beatriz Recari, Paula Creamer, Jodi Ewart Shadoff and Ji Eun-Hee - are a stroke behind in the no-cut 72-player field.
Lang, who teed off from the 10th hole, had the early lead after birdying six times in the back nine on the 10th, 11th, 12th, 13th, 15th and 16th holes.
She took the outright lead on the opening hole with another birdie, but then dropped to second after bogeying the ninth.
"It got a little hot towards the end and I didn't finish off as strong as I would have liked," said Lang.
The Sime Darby LPGA Malaysia is the second of five tournaments in the Asian swing with events in South Korea, Taiwan and Japan to follow.
Leading scores after the first round Thursday in the $2 million Sime Darby LPGA tournament at the Kuala Lumpur Golf and Country Club:
First round (Par 71):
64: Lee Il-Hee (KOR)
65: Britany Lang (USA)
66: Beatriz Recari (ESP), Paula Creamer (USA), Jodi Ewart Shadoff (ENG), Ji Eun-Hee (KOR)
67: Brittany Lincicome (USA), Suzann Pettersen (NOR), Feng Shanshan (CHN), Cristie Kerr (USA), Kim In-Kyung (KOR), Lexi Thompson (USA), Caroline Masson (GER), Alison Walshe (USA)
68: Mina Harigae (USA), Caroline Hedwall (SWE), Jessica Korda (USA), Morgan Pressel (USA), Mamiko Higa (JPN), Anna Nordqvist (SWE)