US Open champion Ryu So-Yeon led a South Korean charge at the top of the Australian Women's Open at Royal Melbourne on Friday.
Ryu, 21, fired a four-under-par 69 to be six-under ahead of compatriot Seo Hee-Kyung (75-66) at five-under.
Ryu tied for second at last week's Australian Ladies Masters at Royal Pines on the Gold Coast and felt she was adjusting well to the Australian conditions.
"(Australian coach) Ian Triggs is travelling with me last week and this week," she said. "He is a coach but feels like a father, so maybe I feel more comfortable here."
She said she was too nervous in last weekend's final round and feels her coach's advice to take a deep breath and settle down will serve her well in the Open.
"I think the reason was that I really wanted to win the tournament. I think it was really high expectations of myself. I was thinking about winning and the trophy and maybe I lost concentration," Ryu said.
Seo said she was also tentative coming into the Open, wary of Royal Melbourne's tough reputation and which was the venue for last year's President's Cup.
"It is very hard to play this great course," Seo said. "I know it is not an easy course so I was nervous."
Seo fired a brilliant seven-under-par 66 in a round which included nine birdies and two bogeys.
Four players were in a tie for third at four under, including Jessica Korda, the 19-year-old US-born daughter of 1998 Australian Open tennis champion Petr Korda of the Czech Republic.
Defending champion and world number one Yani Tseng (76) toppled from second overnight, succumbing to a quadruple bogey eight at the seventh hole after her tee shot found the trees.
Two successive bogeys followed although she fought back with two birdies on the homeward nine to be level with the card and six off the lead.