Seoul, Sept 7, 2012 (AFP) - Lee fired a five-under par 67 to surge to the front of the field, while Griffin, a natural left-hander who plays right-handed, moved up from second place with a round of 70.
Lee, 25, who spent the last 11 years in Australia where he learned the game, was making only his second start in a OneAsia event and only found out he was going to play in the tournament an hour before tee off on Thursday.
"I wasn't really in great shape for this, but I tried my best and it turned out pretty good," he said, according to a OneAsia press release.
"I'm still finding my way so I hope I can keep this up. Making the field was a result, playing the weekend is a bonus."
Griffin has had just one bogey in 36 holes of golf -- but was disappointed to have dropped a few putts.
"The last time I was leading going into the weekend was at least a couple of years ago, at the Australian PGA," said Griffin.
"I have won since, but never had the lead going into the weekend for a while."
The one billion won ($900,000) tournament is being played in Gangwon-do province, which will host the 2018 Winter Olympic games. The venue, South Korea's highest course, doubles as a ski resort in winter.
Scores after round two of the 2012 High1 Resort Open at the par 72 High1 Country Club:
137 - Lee Jun-Seok (KOR) 70-67, Matthew Griffin (AUS) 67-70.
138 - Kim Bong-Jin (KOR) 67-71, Scott Arnold (AUS) 70-68.
139 - Aaron Townsend (AUS) 70-69, Choi Ho-Sung (KOR) 71-68, Song Young-Hoon (KOR) 74-65, Han Min-Kyu (KOR) 68-71, Lee Tae-hee (KOR) 72-67.
140 - Park Sang-Hyun (KOR) 69-71, Cho Min-Geun (KOR) 69-71, Jason Kang (USA) 66-74.