Instead of heading deep down the leaderboard, Grier finished in a tie for 48th, eight shots behind Violeta Retamoza, who played with Grier and rumbled home with a 5-under-par 67 for a share of the lead.
Grier will tee off at 1 p.m. today on the back nine. The top 70 players and ties advance to Sunday's final round.
Dallas native Taylor Leon, who has won two of the last five tournaments, posted a 67 in the afternoon round to share the lead with Retamoza, who hails from Aguascalientes, Mexico.
"Overall, I feel good about my round," said Grier. "I had a bad start on each nine, but I played respectable."
The 22-year-old Grier, starting her round on the back nine, opened with a par but followed with a double bogey on No. 11 when she hooked her tee shot into the water. She recovered to make five straight pars before a birdie on No. 8, hitting a pitching wedge to within five feet.
On the front nine, she made three par-saving putts from inside 10 feet.
Grier's back-nine string of bogeys began on the 383-yard first hole with a tee shot that landed in the 3-inch thick rough. Her approach fell short, hitting the brick walls that front the elevated green, forcing her to take an unplayable, one-stroke penalty. A clutch 12-foot putt saved a bogey.
Grier birdied No. 5, hitting a 5-iron within five feet of the cup on the 374-yard par 4. She followed on the 187-yard par 3, using a 3-rescue club that put her 10 feet away.
She said her father, Dave, who caddied for her, helped her on the greens reading her putts.
The 22-year-old Grier dropped a shot on No. 8 to fall back to 3 over, but finished on a positive note with a par on the uphill, 383-yard 9th, sinking a 12-footer.
"It wasn't her best ball-striking day," Dave Grier said. "Some of her drives, she had to dig out of the rough and the pitches were hard to get out. She made some mistakes, but overall I thought she played good."
Sunshine and warmer temperatures today will add more bulk to the already-thick rough and speed up the greens, which ran around 11 on the stimpmeter Friday.
"The greens are so true to the roll, you just get the ball on line and you'll make putts," Ashley Grier said. "I've just got to come out and be focused shot by shot."
NOTES: Out of the field of 144, only 11 players finished under par and another 11 ended at even par. ... The winner claims a $14,000 check out of the $100,000 purse and the runner-up wins $10,000. ... Smithsburg golf coach Dan Neff served as a scoring official for one of the afternoon groups and will do so again today.