Yin put her extraordinary power to great use at the Sky 72 GC Ocean Course in Incheon with six birdies and an eagle on her way to a 7-under 65 and a two-shot lead heading to the weekend.
Lee, who began the day with a share of the lead, was far from her best Friday and slid down the standings with a 1-under 71, four birdies offset by three dropped shots to slip to T10.
A tap-in birdie at the par-5 18th after a brilliant splash from the greenside bunker saw her finish on a high note but she will begin Saturday four shots adrift of leader Yin.
The 19-year-old American has been touted as a potential superstar since joining the LPGA at the start of 2017 and is delivering on that promise.
A standout at the recent Solheim Cup after being a Captain’s pick, the Californian has put herself in position to claim her maiden title at the limited field event though will likely need to overcome the crowd as well as the golf course to prevail.
US Women’s Open champion and local favourite Sung Hyun Park is among Yin’s nearest challengers after a 3-under 69 despite missing several opportunities late in her round.
The 24-year-old said earlier in the week she was feeling the pressure of playing in front of a home crowd after a mid-field finish in a local tournament two weeks ago.
Also at 9-under is two-time major winner In Gee Chun alongside another star of the domestic Korean circuit Jin Young Ko.
Last week’s Ladies European Tour winner Cristie Kerr is one of five players sharing fifth place, fellow Americans Marina Alex and Lizette Salas also at 8-under.
The Australasian challenge looks to rest almost completely in Minjee Lee’s hands as Lydia Ko signed for a 1-over 73 to be 3-under and T25, one ahead of Su Oh who is the last of the Australians in red figures sharing 33rd position.
Sarah Jane Smith is 3-over and T62 while Katherine Kirk is near the tail of the field at 4-over.
PLAYER PROFILE - ANGEL YIN:
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