Leona Maguire shot a four-under-par round of 68 to begin her challenge at the Ford Championship in Phoenix, Arizona, but the Cavan native is well back from the lead after a sensational opening day from New Zealand's Lydia Ko.
The three-time major winner carded the lowest round of her career with an incredible 12-under-par round of 60, which began with four consecutive birdies, while she narrowly lipped out with a birdie putt on 16 which could have seen her hit the magic number of 59.
Incredibly, Ko's career-best round is only enough for a one-shot lead after South Korea's Hyo Joo Kim finished her round with two birdies and an eagle for an 11-under-round of 61, while Nelly Korda remains well in contention on nine-under.
Maguire is one of 18 players in a tie for 34th place on four under after a slow build through her round.
Starting her round on the 10th hole, the 31-year-old made eight pars in a row to start her day, before a birdie and bogey left her at level par through her opening 10 holes.
She put that bogey behind her to birdie three of her next four though, and added one more birdie on the par-four eighth hole (her 17th), for a round of 68.
Maguire is among the early starters on day two, teeing off at 2.55pm Irish time on Friday.
Kildare's Lauren Walsh faces a battle to make the cut when she starts her second round at 3.50pm Irish time.
The 25-year-old is two shots back from the projected cut mark on one under after an opening round 71.
Walsh fought back from a double bogey on the par-four 14th, which saw her drop to two over, and finished impressively with a birdie and an eagle to get under par.
