The 28-year-old, who struggled to a second-round 81 in Ayrshire as she quickly dropped out of contention, lit up this opening four-under-par effort with a hole-in-one at Champions Golf Club in Houston.
Her ace, which came at the third on the Cypress Creek Course, helped Olson take a one-shot lead over 2018 AIG Women’s Open winner Hinako Shibuno, as well as Moriya Jutanugarn and A Lim Kim.
“I hit the ball really well off the tee,” said Olson. “I gave myself some good chances for birdie, but I really made some putts that I definitely wasn't necessarily thinking birdie on, and that helped.
“Obviously, the hole-in-one was kind of the highlight of the round. I was pretty excited to be able to do that at the US Open.”
Given that the Cypress Creek Course played a full stroke harder (74.59 to 73.46) than the Jackrabbit Course, which is co-hosting the first two rounds due to daylight concerns, Olson was delighted with her day’s work.
But the 2018 Evian Championship runner-up after making a heart-breaking double-bogey on the 72nd hole added: “It's not easy to win out here. You have to put four really good days together.”
Shibuno, who was dubbed ‘The Smiling Cinderella’ when she became a major winner on British soil at Woburn, carded four birdies and one bogey on her US Women’s Open debut.
“This is my first time playing two different courses, so that's why I did a lot of practising beforehand. That's why I came in early to fly in,” said Shibuno.
Jutanugarn and Kim both opened on the Jackrabbit Course. Jutanugarn returned a clean scorecard with three birdies, while Kim had an up-and-down round of five birdies and two bogeys.
Seven players are tied for fifth at on two-under, including 2020 AIG Women’s Open champion Sophia Popov and England’s Charley Hull.
Tee times for today’s second round have been moved to 8 am CST from their original starting time of 9:20 am due to anticipated inclement weather.