Ireland's Stephanie Meadow and Italian Giulia Molinaro moved into a share of the lead after carding a second-round nine-under 61 at the Dow Great Lakes Bay Invitational in Michigan.
The pair, playing in the LPGA Tour's first team event, started the day in joint 12th place after a first-round 69 in Wednesday's foursome session.
On Thursday, playing fourballs, Meadow and Molinaro made five straight birdies through holes five to nine to finish on 10-under overall alongside the French pair of Celine Boutier and Karine Icher and the American team of Paula Creamer and Morgan Pressel.
"Steph at the beginning was putting extremely well and made all the putts at the start," Molinaro told LPGA.com.
"When I missed one on a par three, she looked over and was like, 'Hey, we're a team. When one person's not playing well, the other one is going to pick up the slack'.
"And then I managed to roll two of them in... we played well all day. When I was in trouble, she helped me out and vice versa."
Boutier and Icher closed with three straight birdies for a second-round 62 and Pressel and Creamer had six birdies through eight holes to card a 64.
First-round leaders Brooke Henderson and Alena Sharp shot a 66 to sit on nine-under among a six-strong pack in a tie for fourth, while Celine Herbin and Joanna Klatten carded the best round of the day with a 60 to move into joint 14th place on seven-under for the tournament.