A quartet of players shot opening rounds of 69 to tie for the lead at the ISPS Handa World Invitational in Antrim, Northern Ireland, on Thursday.
Playing the par-73 Castlerock Golf Club, Gabriella Cowley of England, Ellinor Sudow of Sweden, Switzerland's Kim Metraux and Australian Karis Davidson finished the round at 4-under par, a stroke ahead of a four-player group tied for fifth.
The field is split the first two days between Castlerock Golf Club and the par-72 Galgorm Castle Golf Club. American Marissa Steen shot the day's low round (70) at Galgorm on Friday and sits in a four-way tie for ninth place at 2-under.
The players will swap courses on Friday, and the final two rounds will be played over the weekend at Galgorm Castle.
Ireland's Leona Maguire, No. 14 in the world rankings, is the highest-ranked player in the field. She shot a 73 on Friday at Castlerock and is four shots off the lead. Defending champion Maja Stark of Sweden is not participating.
Sudow said that despite the logjam at the top of the leaderboard, she is delighted to enter play Friday as a co-leader.
"It's wonderful. I haven't been playing great this year so this is really nice," she said. "I kind of need it both for confidence, and, yeah, it's really nice."
Sudow stood at 1-under par after 13 holes, but three birdies in the final four holes propelled her into the lead group.
Davidson also was happy to land in the co-lead after a round in which the players had to fight the wind and amid a rough LPGA season. She has no top-10 finishes in 12 events and has missed six cuts.
"I'm just going to try and keep doing my own game and try not to think about that too much," Davidson said of her spot on the leaderboard. "But it is nice to see it up there for a change."
She said she is ready to switch courses.
"Galgorm is playing really soft so you can definitely be a little bit more aggressive at pins," she said. "And the greens are a little bit quicker, so it's quite a different golf course. I'm looking forward to the challenge.
In the four-way tie a stroke off the lead are Dani Holmqvist of Sweden, Bronte Law of England, Anne-Charlotte Mora of France and Chloe Williams of Wales.
Joining Steen in the group two strokes back are Wichanee Meechai of Thailand, Germany's Patricia Isabel Schmidt and Moa Folke of Sweden.
—Field Level Media