The 28-year-old Australian, currently 68th in the live rankings, remains a chance of reaching the season-ending Tour Championship, an $US11 million ($A16 million) showpiece featuring only the top 60 in the year-long points race.
Choi, who started the day in 74th, drained birdies on the fourth, 10th, 13th, 14th and 18th holes for a blemish-free five-under-par 67 at the Kuala Lumpur Golf and Country Club on Thursday.
Pauline Roussin-Bouchard of France birdied her final three holes for an eight-under 64 and a one-stroke lead.
The former top amateur, whose rookie season on tour was 2022, is still looking for her first LPGA win and has three top-10 finishes.
"Honestly, today I made some really, really good shots, great putting," Roussin-Bouchard said.
"My challenge today was just to keep the inside voice pretty calm, because I'm not a calm person, but just kind of under control, try not to plan ahead or just like get ahead of myself in any situation.''
American Sophia Schubert, who joined the tour the same year, is tied for second place after a 65 with Japan's Miyu Yamashita, who won last year's Malaysian tournament after a three-way playoff.
Another French player, Perrine Delacour, shot 66 and is tied for fourth with England's Charley Hull, who birdied two of her final three holes.
Haeran Ryu, a major winner this year at the Women's PGA Championship and at the Evian Championship, withdrew before her first-round tee time for an undisclosed reason. She was the highest-ranked player in the tournament in the absence of world No.1 Nelly Korda and No.2 Jeeno Thitikul.
Last week, Yuri Yoshida (69) won the BMW Ladies Championship in South Korea, the fourth Japanese player this season to win on the LPGA Tour, joining Yamashita, Shiho Kuwaki and Yuna Nishimura.
Aussies Cassie Porter (69), Karis Davidson (70), Grace Kim (73) and Hannah Green (74) have some work to do to catch the leader.
Green, in 12th spot, is the only Australian certain to qualify for the LPGA season finale in Naples, Florida, from November 19-22.
But fellow major winner Kim (51st) and Porter (48th) also look likely, with Davidson (60th) walking the tightrope.
The LPGA's four-week, late-season Asian swing ends next week with the Japan Classic at Omitama, outside Tokyo.
With The AP.
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