Each posted rounds of 5-under par as they hold a one-shot advantage over yet another South African, Nic Henning, who fired a 4-under 68.
Two players stand two off the pace and seven more players, including American Scott Dunlap, are three back.
Trevor Immelman, coming off his victory at last week's Dimension Data Pro-Am, had a trying day but still was able to manage a 1-under-par 71. He is seeking his third win of the season.
After picking up his first birdie of the day at the par-4 7th, Immelman double bogeyed the next as things started going sour for the 23-year-old.
On his tee shot at the par-3 seventh, his ball landed in water as he realized his grips were twisting in his hand. He had had the same problem earlier in the week, and thought the problem was solved until that tee shot.
My caddie had my grips redone on Tuesday morning,' noted Immelman. 'In the pro-am, I made a swing which felt OK and the ball went off to the right. Thats when I first saw the grips could twist completely around.
Then his caddie, Neil Wallace, was forced to leave the bag at the ninth hole due to food poisoning.
Apart from a dying caddie and the grips on my clubs, it was a good day, said a smiling Immelman.