Behind them, four more South Koreans and Australian Matthew Griffin were bunched together in a tie for the third place on a day of low scoring in the OneAsia Tour event being played at the par-72 Namseoul Country Club on the outskirts of Seoul.
The 39-year-old Pilkadaris attributed his strong showing on Thursday to the extra effort he put in to improve his game on the greens after struggling over the final three days of last week's China Open, where he played as a late replacement.
"I putted poorly at the weekend - actually the last three rounds were disappointing - and so after the (final) round, I just went to the putting green," Pilkadaris said after his bogey-free round.
Cho also credited his work on the greens as the catalyst for a spotless round.
"My putting was really good today but actually the score looks better than the golf... I was scrambling a bit out there," he said.
Defending champion Kim Bi-o recorded a double-bogey six at the par-four 18th to fall back into a tie for 62nd after an even-par round of 72.
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