JOHANNESBURG, February 8, 2014 (AFP) - A nine under par 63 from Thomas Aiken and an eight under from Justin Walters left the two South Africans a couple of shots clear of the rest of the field on 17 under with one round to go.
Both players were born in Johannesburg.
Walters was off to a flying start when he birdied the first three holes. But that was just the start from the 33-year-old, who secured four more birdies, the last a 40 footer.
But his round was more than matched by Aiken, 30, who carded eight birdies and just one bogey in the first 15 holes.
The South African pair are two ahead of South Korea's Jin Jeong, who's good form at the Royal Johannesburg & Kensington Golf Club continued.
He posted a six under 66, to go alongside a 65 and a 69 earlier this week, to finish on fifteen under for the first three rounds.
A shot further back is Finland's Roope Kakko who shot a 67 on Saturday.
The overnight joint leader Edoardo Molinari could only manage a level par round leaving him six shots off the lead.
But that was better than the other co-leader at the start of play, Scotland's Craig Lee, managed. He shot a two over 74, to finish eight strokes off the lead.
The field were playing on the East Course. During the first two rounds the field had also played on the West Course.
The winner of the Joburg Open will take home 206,050 euros and one of three automatic qualifications for the British Open.
Leading scores on Saturday in the third round of the $1.77m Joburg Open on the European Tour on the East Course of the Royal Johannesburg and Kensington Golf Club (par 72):
198 - Thomas Aiken (RSA) 70 65 63, Justin Walters (RSA) 64 70 64
200 - Jin Jeong (KOR) 65 69 66
201 - Roope Kakko (FIN) 70 64 67
202 - Alastair Forsyth (SCO) 64 70 68, George Coetzee (RSA) 65 68 69
203 - David Horsey (ENG) 70 63 70
204 - Edoardo Molinari (ITA) 64 68 72
205 - Byeong-Hun An (KOR) 69 68 68, Brandon Stone (RSA) 68 67 70, Danny Willett (ENG) 69 65 71, Matthew Baldwin (ENG) 68 69 68, Gary Stal (FRA) 66 69 70, James Morrison (ENG) 70, 66, 69, Anthony Wall (ENG) 69 70 66, Tyrrell Hatton (ENG) 67, 69, 69, Gregory Bourdy (FRA) 68,67, 70
206 - Craig Lee (SCO) 65 67 74, Robert Jan Derksen (NED) 65 74 67, Ross Fisher (ENG) 69, 69,
68, Robert Dinwiddie (ENG) 68, 70, 68, Jaco Van Zyl (RSA) 70 68 68, Seve Benson (ENG) 68, 68,
70, Alvaro Quiros (SPA) 69 68 69, Andrew Georgiou (RSA) 69, 65, 72, Emiliano Grillo (ARG) 68, 69, 69, Danie Van Tonder (RSA) 65, 72, 69, Drikus Van der walt (RSA) 66,71, 69, Peter Karmis (RSA) 73, 65, 68
207 - Justin Harding (RSA) 66, 72, 69, Jorge Campillo (SPA) 67 69 71, Andrew Sullivan 66, 72, 69, Christiaan Basson (RSA) 71, 65, 71, Erik van Rooyen (RSA) 69, 70, 68, Ariel Canete (ARG) 70 68, 69, Lorenzo Gagli (ITA) 68 71 68, Adrian Otaegui (SPA) 71, 68, 68, Louis De Jager (RSA) 68, 70, 69