Jon Rahm was the star of the show on Friday at the CJ Cup, shooting a nine-under 62 to jump all the way up into a share for first place at 11 under with Kurt Kitayama.
Rahm's 62 came after an opening 69, raising his birdie count from six to 10, while cutting his bogeys from four to one as he figured out the Congaree Golf Club course.
Kitayama has been a much steadier presence this week, posting rounds of 66 and 65, with his second round highlighted by an impressive eagle on the par-five 12th hole.
Those two players lead the pack by one stroke, with Australia's Cam Davis and America's Aaron Wise tied for third at 10 under with back-to-back 66s.
Rory McIlroy is alone in fifth at nine under after following a front-nine score of 37 with an impressive 30 on the back-nine, and he is two strokes clear of a logjam tied for sixth at seven under.
The group includes young phenom Tom Kim, as well as former major champion Shane Lowry and England's Tyrrell Hatton, while Masters champion Danny Willett is a further shot back at six under.
Presidents Cup representatives Max Homa and Im Sung-jae enter the weekend six strokes off the pace at five under, with former world number one Jason Day at four under and current world number one Scottie Scheffler at three under.
Being an invitational event with no cut, Collin Morikawa (three under), Rickie Fowler (two under), Justin Thomas (one under) and Hideki Matsuyama (even par) will all get to stick around and play two more rounds.