Coughlin builds five-shot lead at LPGA Aramco Championship
Coughlin had six birdies and three bogeys as she matched the low round of the day at Shadow Creek, where her eight-under par total of 136 put her five clear of Ireland's Leona Maguire and South Korean Kim Hyo-joo.
Coughlin, who finished runner-up to Madelene Sagstrom when the tournament was a match play event last year, said she played "really, really good" in "really difficult" conditions.
"The wind was kind of swirling at times and a lot of crosswinds," she said. "Very difficult. The greens firmed up as they do in the afternoon, especially with the wind.
"But, yeah, really, really solid round. Had a lot of fun out there. Looking forward to the weekend."
Maguire had four birdies and three bogeys in her one-under 71 and was joined on three-under 141 by Kim, who is coming off back-to-back LPGA victories at the Founders Cup and Ford Championship.
Kim had a double bogey and three bogeys but nabbed the last of her four birdies at the par-five 18th to complete a one-over 73.
"Going out, we knew it was going to be tough," Maguire said. "Obviously a lot windier, different wind than we got all week as well, which made some holes play quite a bit longer.
"We knew we were going to get the firmer end of the greens this afternoon, so just a case of staying extremely patient."
Despite the testing conditions, Maguire welcomed the test posed by Shadow Creek.
"It's a fantastic golf course," she said. "It's one of the best courses we play all year."
As a dual member of the LPGA and the Ladies European Tour she was relishing this week's co-sanctioned event, which is part of the Saudi-backed Global Series and features a total purse of $4 million with a $600,000 winner's prize.
"This is a huge event for both tours," Maguire said. "Outside of the majors this is one of the biggest there is and a huge opportunity for everyone early in the year to do well."
The field features all of the top 20 in the world rankings.
World number two Nelly Korda headlined a trio sharing fourth on two-under 142.
Korda carded a two-over 74 and was tied with Denmark's Nana Koerstz Madsen and overnight co-leader Miyu Yamashita of Japan.
Koerstz Madsen carded a two-under 70 while Yamashita, the reigning Women's British Open champion and last year's LPGA Rookie of the Year, posted a three-over 75.