CHRISTCHURCH, New Zealand – Lydia Ko has a new accessory on her hand this week. Her U.S. Women’s Amateur champion’s ring arrived Wednesday, and she’s wearing it proudly, as it looks like one of the class rings from American movies that she has coveted. It’s the only thing about Ko that screams amateur.

“You never know when you’re watching history,” Angela Stanford, the highest-ranked player in the field at the ISPS Handa New Zealand Women’s Open, said of young Ko. Stanford had a miserable two days around Clearwater Golf Club – missing the cut in the Ladies European Tour event – but has played the last three days alongside Ko. During the Thursday pro-am, Ko was one of Stanford’s amateur playing partners. Even then, Ko hit last.

Ko posted a tidy 4-under 68 on Day 2 of her national open to stand tied for the lead with South Korean Seon Woo Bae (74-64) at 6-under 138 heading into the final round. This week is likely the only time Ko will play in New Zealand in 2013, apart from the NZ PGA Pro-Am Championship, a men’s event with a format that’s similar to the AT&T Pebble Beach National Pro-Am. She’s the only New Zealander to make the cut this week.

“I’ve played good in other countries’ opens,” said Ko, referring to the CN Canadian Women’s Open, which she won last summer at age 15.

Incidentally, she’s still 15.

Since Ko became the youngest player in the LPGA history to win in Canada, she has grown two inches and added 20 yards of distance off the tee, yet managed to stay unflinchingly accurate.

Case in point: the par-5 14th hole. Ko had 231 yards left after her drive and slashed a 3-wood to

36 feet just over the green. She left the flag in the hole and drained the eagle putt to kickstart her Saturday stroll.

“There was really nothing to complain about today,” said Ko, who almost immediately then mentioned the three-putt she had from 12 feet on the seventh hole (her 16th).

On the par-4 sixth, Ko stood waiting in the fairway for her playing competitors, who were well behind her and in the rough. Ko’s accuracy enabled her to hit driver off the tee while the others tried to thread fairway metals. Shortly after Ko stuffed her approach, her swing instructor Guy Wilson, standing nearby against a rope, yelled “Let’s go, robot! Do it.”

Ko simply lifted a finger up to her lips, shushing him.

“She’s telling me to keep quiet so I don’t embarrass her,” Wilson said.

Judging by last summer’s back-to-back performances at the U.S. Women’s Amateur and Canadian Open, Ko is not likely to collapse Sunday. She has been seeing a sports psychologist weekly for the past four years, working as diligently on her mind as she does her body.

When a friend told Ko that he needed only 24 putts in a tournament round after getting hypnotized, Ko asked psychologist David Niethe to put her under.

“At first, I found it so funny I couldn’t do it,” said Ko, thinking of folks she’d seen on TV clucking like a chicken.

“The subconscious mind is basically the one doing it,” Ko said. “Not me.”

Whatever spell Lydia Ko is under, it’s a spectacular sight. Sunday could turn out to be a very special day for the world’s most talented amateur.