Ramsay was on the back foot straight away after opening with back-to-back bogeys at Vallda Golf Club outside of Gothenburg before turning his day round with a blistering burst.
He’d already picked up a birdie at the fourth before reeling off four in a row from the sixth then starting for home with an eagle-3 to share the lead.
The Aberdonian moved to six-under after another gain at the par-4 14th before a dropped shot at the 17th left him signing for a five-under 67.
That was later matched by David Drysale, who carded an eagle and five birdies, as the Scottish duo ended the day in a tie for 11th spot.
As the set up for the ground-breaking event delivered exactly what Sorenstam and Stenson had been hoping for, Austrian Christine Wolf and England’s Sam Horsfield set the pace with matching 64s from different tees.
“It was a bit of a rough start,” said Ramsay of his effort. “Any time your alarm goes off with a four at the start, it’s not good.
“I woke up on the third hole, had a nice little run and caught fire. A couple of up and downs I didn’t make, but all in all it was very good as it’s very firm and fast out there.”
The historic event involves 78 men and 78 women going head-to-head for the same trophy and same €1m prize fund.
“I haven’t played with any of the women for a long, long time. It was quite refreshing,” added three-time tour winner Ramsay.
“It’s very hard to set up when you have male and female players, but they did a really good job with the set up.
“It’s something different, it’s refreshing. If you play the same old format, 72-hole stroke play every week, after a while I’m sure people at home are thinking we need something a bit different. Whether it be team golf, Sixes, male and female. It’s nice to do that and change it up.”
Alison Muirhead was best among the Scottish women with a three-under 69.