The South Korean star shot a sparkling 6-under 66 to take a one-shot early lead in the clubhouse over Australian Nikki Campbell and England's Felcity Johnson.

The duo fired matching 67s to in turn edge by a shot the three Australians in third place, Frances Bondad, Courtney Massey and Sarah Kemp.

But their were rivals, still out on the course, capable of catching them before the day was out.

Ryu didn't try to hide the fact that she had battled to overcome some early nerves in this, her first competitive outing this season, but acknowledged that once she had found her momentum, she had a "lovely day" as she picked up three birdies on each of the two nines in her bogey-free round at a Royal Pines Course that was still soggy, but playable after heavy rain earlier in the week.

She said, enthusiastic as ever, "It was a great gallery, great caddie, it was a lovely day for me.

"But I was really nervous because it was my first tournament of the year," she said, when explaining that the weight of expectation from her fans at home had initially weighed heavily on her until her first birdie helped boost her confidence and calm her down.

"I can't believe it. Yesterday the course was too wet, but today it was a lot better."

The caddy Ryu was talking about is Tom Watson, a 33-year-old Australian who has been working in Japan and this week is on trial prior to joining Ryu on a full-time basis

Watson, whose middle name is Jack after Jack Nicklaus, comes from passionate golfing family.

His father Peter played inter-state golf while his mother Cheryl was born on the same day in the same year as American legend Tom Watson.

But Ryu credits his experience in Asia as one of his most valuable assets.

"Tom was a good advisor to me," she said. "He really knows the Asian culture, because he lives in Japan, so it's a lot of help to me.