Leona Maguire is six shots off the lead after day one of the season-ending CME Group Tour Championship in Florida.
The Cavan golfer, seeking a first win in 17 months, carded a two-under par round of 70.
South Korea's Somi Lee carded an 8-under-par 64 to take a two-stroke lead over Allisen Corpuz in Florida.
Maguire's round was soured by three bogeys, including dropped shots on the first and fourth holes, at Tiburon Golf Club.
The 30-year-old picked up shots on the fifth and 13th, and bounced back from a six on the par-five 14th with a run of three consecutive birdies to finish the day tied for 32nd place.
Lee got to 9 under after making an eagle on the par-5 17th hole, but suffered her lone bogey of the day on the last hole. She made seven birdies in her first 15 holes around Tiburon Golf Club.
"My tee shot and putter was the things I was focusing on and I really practiced them a lot," Lee said through a translator. "I think that was the foundation to my success today."
Corpuz started slowly, bogeying the third hole, then rattled off four consecutive birdies to get her round in gear. She added three birdies on the back nine as she started to feel more comfortable in the surroundings.
"I think every year I come back and the course feels a little friendlier," Corpuz said. "It's been really cold for the last few years as well and I think it's played a little shorter with it being a little warmer, which always helps me."
Only the top 60 players in the season-long standings qualified for the season finale, with a purse of around €9.5 million on the line and €3.5m of that available to the winner, one of the biggest prizes in women's golf.
Additional reporting: Reuters
