David Lipsky fired a bogey-free 66 to set the clubhouse target and open up a one-shot lead on day two of the Alfred Dunhill Championship.
The American is making his first appearance at Leopard Creek Country Club this week and an eagle and four birdies moved him to eight under as he made himself right at home.
Scott Jamieson has two top fives in this event and he continued that form to match Lipsky's score and sit at seven under alongside fellow Scotsman Marc Warren.
Doug McGuigan made seven birdies on the back nine to record the lowest nine holes of the season and make it three Scots in the top four a further shot back.
Home favourites Oliver Bekker, Darren Fichardt and Dylan Frittelli were three shots off the lead alongside England's Oliver Wilson.
Lipsky made a birdie on the 11th and an eagle on the 13th but overnight leader Bekker birdied the 12th to jump out to seven under.
The home favourite then double-bogeyed the 13th and dropped a shot on the 15th to fall back, with Lipsky making a gain on the 16th to jump out in front.
Jamieson then joined him at the top with a stunning run of birdies, making gains on the 13th, 14th, 15th, 17th and 18th to turn in 32.
Lipsky made birdies on the second and third to lead by two and when Jamieson bogeyed the second, the advantage was three shots.
The 35 year old picked the shot straight back up on the next and made a gain on the sixth to cut the advantage back to one as Lipsky parred his way home.
Warren had to go to the Qualifying School to regain his card in November and started the season with a top 25 in Johannesburg last week.
He made a moved up the leaderboard with birdies on the tenth, 13th and 14th but sandwiched another gain on the 16th with a pair of bogeys to turn in 35.
A big finish then fired him up the leaderboard with gains on the fifth and seventh and a holed bunker shot on the eighth.
McGuigan had bogeyed the first and fifth but a birdie on the eighth was the first of eight in 11 holes, as he made four in a row from the tenth and picked up shots on the 15th, 16th and 18th.
Playing partners Fichardt and Frittelli both made five birdies and three bogeys in rounds of 70, while Bekker eventually signed for a 73.
Wilson is playing by virtue of a top ten last week and he made a fast start with a hat-trick of birdies from the 13th but dropped shots on the 16th and 18th before picking them back up on the first and third.
Four -time Major winner Ernie Els fired a 67 to sit at four under alongside Ben Evans, Niklas Lemke - who finished his 68 with six straight birdies - and Zander Lombard.