The 16-year-old shot a one-over par 73 on the opening day at the Mission Hills Country Club, leaving her seven shots off the pace in a share of 29th.
If Ko is able to rally and win the tournament, she will break a 146-year-old record as the youngest golfer to claim a major, but that will require quite a turnaround when she tees off for her second round tomorrow morning.
The world No 4 started her round on the 10th and was even through the first six holes, before she dropped a shot at the 16th. Ko then birdied the 18th to head to the turn on even par, but a double bogey at the par-four first hole sullied her round.
After gaining a shot back with a birdie at the seventh, Ko finished her round seven shots back from leader Shanshan Peng of China. The Kiwi was not alone in experiencing an uneven first round, with world No 1 Inbee Park shooting a two-over 74 to sit one shot behind Ko.
