Thitikul completed a bogey-free eight-under-par 64 with a hat-trick of birdies to storm to the top of the leaderboard at the Kuala Lumpur Golf and Country Club on Saturday.
The resurgent former world No.1 ignited her round with an eagle three on the third hole, then collected six birdies to surge from eight to 16 under for the championship.
"It's been like a heaven week, to be honest," Thitikul said.
"You know, like KL (Kuala Lumpur) is close to Thailand and I feel like it's a second home here. All the fans cheering out here, it's really nice and amazing to be here. And then also the golf course, it's one of my favourites so far."
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Thitikul was joined atop the leaderboard by rising Korean star Haeran Ryu, who also went bogey-free in a third-round 67, and China's world No.4 Rioning Yin (66).
Swedish halfway leader Maja Stark (70) is one shot behind the front-runners at 15 under, with the chasing pair enjoying a three-stroke buffer over France's defending champion Celine Boutier (68) in fifth place.
"Obviously it's good to have memories and stuff, but also know I have to focus on what I'm doing and I feel like this course is pretty score-able so you have to go out there and be aggressive," Boutier said.
After starting the day only three shots off the pace, Ruffels could only manage a one-under 71 to fall six strokes adrift of the leaders.
The 24-year-old picked up two birdies in the opening four holes to briefly edge to 11 under and within two of the early third-round lead before stumbling with bogeys on nine and 13.
Australian Hannah Green fired a third-round four-under 68 to be eight under. (AP PHOTO)
Ruffels remains the top Australian in a tie for 10th at 10 under with Malaysian amateur Mirabel Ting, two clear of Hannah Green, who steadily climbed the leaderboard in to a six-way share of 19th with a bogey-free 68.
While unlikely to secure back-to-back victories after claiming her third win of the year last week in Korea, Green's move gives the West Australian a last-day shot at rising to a career-high No.4 in the world.
Grace Kim crashed with a 73 to slip back to three under, in a tie for 49th in the 55-player field with fellow Australian Hira Naveed, who jumped up 16 spots with a 68.
With the AP.
