Pace shares second place on the leaderboard with American Austin Ernst, while Laura Diaz of the US holds the lead after a flawless 62 at the Highland Meadows Golf Club in Sylvania with three rounds left to play.
Pace and Ernst were one shot clear of half-a-dozen players on four under, including world number two Lydia Ko, Sunshine Ladies Tour regular Katie Burnett and Mo Martin.
Martin is chasing back-to-back victories after her British Women’s Open triumph on Sunday.
South Africa’s Ashleigh Simon opened with a one under 70 to tie for 33rd and compatriot Paula Reto returned a 73 to finish joint 74th.
Pace had a lone bogey at the par-four 12th, but negated the damage with a birdie at the par-three 14th and a brace of birdies at the 16th and 17th to turn in 35.
The 33-year-old drained a 25-foot slider for birdie at the par-four third to dip to three under, and knocked in two putts inside two metres for another pair at the sixth and seventh to complete the loop in 31 strokes.
“I’m really happy with this round,” the eight-time Ladies European Tour winner said.
“I think the greens are quite receptive. I just hit it on the good side of the hole and pretty close. I’ve just been striking my irons really well and shaping it into the holes.”
The former Ladies European Tour number one said a good result had been on the cards.
“I’m very happy the way I’ve been playing for the last few weeks. From the US Open, I started striking the ball really well.
“It’s nice to be out on the LPGA for a change and see what I can do here and hopefully I can carry that through to the weekend.”
Meanwhile, on the Ladies European Tour Nicole Garcia was the best of the South Africans with an opening four under par 68 to move into the top 12.
Stacy Bregman compiled an opening 70 for the share of 31st, while Connie Chen carded a 71 and Kim Williams shot a 72.