"Hit two poor irons, actually, three poor irons in my first five holes," van Dam said. "I wasn't really swinging that freely. So I just said to myself, 'Go on and play golf, hit shots, and don't try to think too much about technique, just play your shots.'"
Van Dam has struggled in her first season on the LPGA Tour, breaking 70 for only the fifth time in 17 rounds. She has four victories on the Ladies European Tour, winning in early March in Australia, and leads the LET Solheim Cup points list.
"It's nice to finally get off to a good start in the first round," van Dam said. "I feel like I have been close, but just a few bad holes every week I had so far, a few like doubles and triples, which out here you fall back 20 spots."
She's comfortable at Lake Merced. "I feel like this golf course is set up perfect for me," van Dam said. "I can hit long drivers and can be aggressive with my short irons. So, I really enjoyed the course."
Ryu closed with a bogey on the par-5 ninth. The South Korean had seven birdies and two bogeys. "Not really easy golf course," Ryu said. "You have to drive the ball really well. Everything has to be really great to shoot the low score."
Ryu has six LPGA Tour victories, winning major titles in the 2011 U.S. Women's Open and 2017 ANA Inspiration. She's trying to be easier on herself on the course "It's really tough, because when you're dedicated to make your game better and better, and then when you cannot really see the result right away, it can be really easy to get frustrated." Ryu said. "The thing is, it's just golf. Nothing's really guaranteed."
Ji had six birdies and a bogey. "It's a really nice golf course," the South Korean said. "It's really challenging on every hole, especially on tee shot. We have to make the fairway for next shot. If not, get into trouble. Tee shot is really important. Greens are really tough out there. We have to read perfect lines."
The 2009 U.S. Women's Open champion won the season-opening Diamonds Resorts Tournament of Champions for her fifth LPGA Tour victory. After offseason swing changes, she has four top-seven finishes in eight events this year.
"Especially, on my backswing," Ji said. "I'm flatter a little bit and smaller backswing, so makes me more compact. That makes a lot different." Celine Boutier, Amy Yang and Peiyun Chien were a stroke back at 68. Boutier had six birdies in a seven-hole stretch on her final nine. Yang birdied five of her last six holes.
In Gee Chun, Charley Hull, Azahara Munoz and Moriya Jutanugarn topped the group at 69. Defending champion Lydia Ko had four bogeys in a 75. She also won at Lake Merced in 2014 and 2015 when it hosted the Swinging Skirts LPGA Classic.
Brooke Henderson, the winner two weeks ago in Hawaii, bogeyed the 18th for a 72. Playing partner Minjee Lee, coming off a victory Sunday in Los Angeles that moved her to No. 2 in the world, had six bogeys in a 76.
Americans Lexi Thompson, Stacy Lewis and Jessica Korda also struggled. Thompson had five bogeys in a 73, Lewis had a double bogey and three bogeys in a 76, and Korda had a triple bogey, a double bogey and three bogeys in a 79.