As many of women's golf's premier players faltered down the stretch, Lee and Green excelled to finish as joint leaders after Saturday's third round at Sentosa's Tanjong Course.
A Sentosa specialist having won in 2024 and finished runner-up in 2021, Green fired the equal round of a day, a savvy four-under-par 67, to vault to 11 under overall.
"I love coming to Singapore," said Green, who has her pro-playing husband Jarryd Felton as caddy.
"I don't typically hit a lot of fairways but I hit a lot of greens here and I think that always helps around this golf course.
"But having a lot of familiar faces amongst the crowd is really nice and having my husband by my side, as well, it's been a lot of fun."
After struggling to find her A game following a Friday 64, Lee showed her class with three late birdies to post a 68 and join her fellow Perth prodigy atop the leaderboard.
Triple major winner Lee laboured through her first 11 holes in even par before bursting to life with birdies on 13, 14 and 17 to break from the pack chasing South Korean halfway leader Haeran Ryu.
Green mixed five birdies, including three straight early on the back nine, with just one bogey to capture the early clubhouse lead - before Lee joined her.
Lee and Green are both major champions and share the same wizardry coach, setting the scene for a fascinating final round on Sunday.
"I don't actually feel like we've played that much over years together," Lee said.
"We played a few practice rounds, or a few rounds back at home in the off-season but, yeah, I think it will be a fun challenge tomorrow.
"I'm sure we'll have a good time, anyway."
The WA duo hold a tenuous one-shot lead over Ryu, who posted a third-round 70, and American Angel Yin, who matched Green's Saturday 68.
