Charley Hull and partner Michael Brennan were one of two teams to set a new scoring record at the Grant Thornton Invitational, posting a 17-under 55 on day one of the mixed-team event.
Lexi Thompson and Wyndham Clark are tied for the lead after also carding a 55 opening round, both teams making only three pars in the scramble format.
Hull and Brennan at one stage went 13 straight holes with a birdie or an eagle, but had to settle for pars on the 16th and 18th holes.
Brennan, who started the year on the PGA Tour of Americas and won the Bank of Utah Championship on an exemption, was filling in for Daniel Berger who was originally due to partner Hull.
Thompson and Clark made birdie or eagle on nine of the last 10 holes, with the only exception being the par-three 16th.
The 55 recorded by both pairs broke by one the previous record round at the mixed-team event featuring PGA and LPGA Tour players that began three years ago.
They hold a two-shot lead over Lauren Coughlin and Andrew Novak on 15 under. Rose Zhang and Michael Kim, Nelly Korda and Denny McCarthy, and Jennifer Kupcho and Chris Gotterup are one further back going into day two.
Defending champions Jake Knapp and Patty Tavatanakit were seven under through six holes and played the last seven holes in five under to post a 59 that places them four shots off the pace.
The format shifts to foursomes for Saturday, with Sunday's final round modified fourballs.
The 54-hole competition is a mixed-team event that sees 16 LPGA Tour and 16 PGA Tour professionals compete together in a unique co-sanctioned tournament.
The three-day tournament offers three different formats of team play and allows the 32-player field to compete for equal prize money and visibility.
It is the second successive year the tournament has featured on the schedule, having been launched in 2023 as the first co-sanctioned event between the LPGA Tour and PGA Tour since the JCPenney Classic in 1999.
Watch the Grant Thornton Invitational throughout the week live on Your Site. Live coverage from the second round starts on Saturday from 7pm on Your Site Golf. .
