Leona Maguire produced a blistering five-under-par opening round to sit one stroke off the lead at the Dana Open in Ohio.
The trio of Carlota Ciganda, Hye-Jin Choi and Ruoning Yin lead the way after first-round 65s, but the Cavan golfer is right in the mix.
Stephanie Meadow is level-par after her first round.
Starting on the 10th hole, Maguire opened with three pars before rolling in a 25-foot putt for birdie at 13. Further birdies would be collected at the 18th, third, fourth and seventh holes on a round that was clear of dropped shots.
Meadow had no such luck with three bogeys as well as a double at 11, but five birdies across her round would limit the damage.
Spanish veteran Ciganda and Korean rookie Choi had bogey-free rounds with six birdies, while Chinese 19-year-old Yin made five of her seven birdies on the back nine at Highland Meadows Golf Club.
They held a slight edge over a star-specked group tied at 5-under 66: Maguire, American Lexi Thompson, New Zealand's Lydia Ko, Denmark's Emily Kristine Pedersen, Aline Krauter of Germany, South Korea's Hyo Joo Kim, Amy Olson and Lauren Stephenson.
Though Ciganda hasn't won on the LPGA Tour since 2016, she has racked up six career Ladies European Tour titles, most recently in July in her native Spain.
She credited her recent success to a caddie swap.
"I have a new caddie that we started at the end of last year, and it's beengood," Ciganda said. "It's taking time for us to get to know each other, buthe's really good on the greens and gives me a lot of confidence on my putting."