Thriston Lawrence started the day one shot off the lead and closed with a 67 to take a three-shot lead into the final day at the Joburg Open,
A win on Sunday would be his fifth on the DP World Tour and his third on home soil.
"I had a game-plan and it was to try and play the exact same golf as I did the first two rounds and I executed it. I stayed nice and patient.
"I could have gone lower, not a lot of made putts, there was a couple at the end that I could have made but it's job done and I'm happy with it.
"The game-plan is exactly the same tomorrow, I'll try and make a few more putts than today but I'm very happy with the game, I'm playing really well so same game-plan."
Dean Burmester moved up into second place at 12-under with a 68 while overnight leader Nikhil Rama suffered from a double bogey at the par-4 first hole, as well as three bogeys and three birdies for a 72, and lies in a share of third place at 11-under alongside Jacques Kruyswijk (69).
Zander Lombard completes the all-South African top-5 at 10-under after carding a 69.