Sergio Garcia continued his stunning performance on day two of the Nedbank Golf Challenge hosted by Gary Player as he maintained a four-shot lead in Sun City.
A remarkable 64 on day one at Gary Player Country Club saw him equal the biggest first-round lead of the season and two birdies in his first four holes saw him stay bogey-free as he moved to ten under.
Home hero Louis Oosthuizen and Finn Mikko Korhonen were then at six under, a shot clear of English pair Ross Fisher and Matt Wallace, and China's Li Haotong.
Garcia is looking for a first Rolex Series win and a second consecutive victory after his triumph at the Anadalucia Valderrama Masters hosted by his own foundation.
Oosthuizen got within four from ten feet at the first but Garcia holed a 24-footer on the same hole to briefly extend his lead to five.
Playing partner Korhonen followed the leader in from six feet to cut the gap and a nice chip from Oosthuizen on the second meant there were two players within four of the lead.
Garcia was over the back of the second green but got up and down to again lead by five before Oosthuizen holed a mid-range putt for a third birdie in four holes on the par-three fourth.
Korhonen then hit a nice approach into the third to get to six under and made an excellent par save on the fourth.
Li needs a win in Sun City to have a chance of winning the Race to Dubai next week and he made a stunning start, making the most of the second, holing a very long putt on the third, hitting a nice approach into the fifth and leaving himself a tap-in on the sixth.
Wallace also birdied the second and a wonderful approach produced a tap-in birdie at the fifth.
Fisher eagled the second and made a long putt on the fourth before chipping in at the seventh to make a big move.
Frenchman Mike Lorenzo-Vera started with four pars to sit at four under, a shot ahead of defending champion Branden Grace, fellow South African Charl Schwartzel, Ireland's Shane Lowry, Englishman Aaron Rai and China's Wu Ashun.
Belgian Thomas Detry was also three under after birdieing six of his first seven holes after starting on the tenth.