New Zealand amateur golfer Lydia Ko is one shot off the clubhouse lead following her opening round in the defence of her NSW Open title.

The 15-year-old hit three birdies and an eagle to fire a five-under 67 at Oatlands Golf Club, one shot behind a trio of players at six-under including Australian amateur Minjee Lee.

Ko, the number one ranked amateur in the world, made history at the NSW Open last year when she won the tournament by four strokes to become the youngest person ever to win a professional golf tour event.

She went on to have a whirlwind season of success - most notably claiming the Canadian Open title by four shots to become the youngest winner on the LPGA Tour and the first Kiwi to do so.