She’s the reigning US Open champion but South Korea’s So Yeon Ryu admitted battling early nerves before firing an impressive opening round of six-under-par 66 in the Australian Ladies Masters.

Ryu wrung six birdies from the damp Royal Pines course in her unblemished round on Thursday.

It was a promising start too for well-named Tom Watson, a 33-year-old Victorian who is on trial this week to be on Ryu’s fulltime caddie.

A fulltime bagman in Japan, Watson made an good impression on the bubbly Ryu as they picked up three birdies on each nine.

“It was a great gallery, great caddie, it was a lovely day for me,” said Ryu.

“I was really nervous because it was my first tournament of the year.”

“I can’t believe it, yesterday the course was too wet but today it was a lot better.”

Ryu said the first of her six birdies calmed her nerves but admitted also feeling added weight of expectation from the public back home following her maiden major title.

Watson, whose middle name is Jack after Jack Nicklaus, has golfing links all through his family.

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

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

“Tom was a good advisor to me,” Ryu said.

“He really knows the Asian culture, because he lives in Japan, so it’s a lot of help to me.

Ryu said she and Watson shared an addiction to the sweeter things in life which gave them something to talk about.

“Our conversation was almost all chocolate and food,” she said. “We both really love chocolate so we talked a lot about chocolate.”

Canberra’s Nikki Campbell was next into the clubhouse with a five under 67, a score matched by England’s Felicity Johnson.

Three Australians, Frances Bondad, Courtney Massey and Sarah Kemp played solidly to all finish on 68.