Aiken completed 54 holes at 18-under-par 198, which matched the tournament's 54-hole scoring record. David Frost was the first to post 198 in 1997 and he was matched by Adam Scott in 2001.
'I had no idea what the record was,' said Aiken of the course record. 'I heard a couple of mutters, but nothing confirmed. I hit a good shot off the tee at the last, and I was on the fairway and I had a 4-iron to the green. Fortunately, I struck it well and that was that.'
Len Mattiace, who shared the lead after the first and second rounds, carded a 6-under 66 and is alone in second at minus-17.
David Lynn (66) and Richard Sterne (68) share third place at 14-under-par 202 with second-round co-leaders Robert Rock (69) and Oskar Henningsson (69). Sterne and Henningsson both double-bogeyed the par-5 18th to close their rounds.
Aiken, who will go for his first European Tour crown on Sunday, did most of his damage in the middle of his round at Leopard Creek Country Club.
The South African birdied the par-5 second to move to 8 under. He birdied seven of the next nine holes to soar into the lead.
Aiken converted back-to-back birdie chances from the fifth, then poured in four consecutive birdies tries from the eighth. His third birdie in three days at the par-5 13th gave him the lead at 15 under.
He settled down with three straight pars. Aiken ran home a 35-foot birdie putt at the par-4 17th, then closed with an eagle at the last to cap a bogey-free round.
'It was a fantastic day. I had a great day (Friday) and just came out here trying to follow that 65 up and try and keep among the pack of the leaders,' Aiken stated. 'It's this funny old game called golf. You just plod along and all of a sudden, things start to happen and you get the ball rolling, sink a few putts and next thing you know you hit 11 under par.'
Mattiace, who has fallen out of the top 1,000 in the world rankings, flew out of the gate with birdies on three of the first four holes. As he parred seven in a row from the fifth, Aiken flew by him into the lead.
The 41-year-old Mattiace birdied the 12th and 15th, but now was two strokes behind Aiken. Mattiace stumbled to a bogey on the 17th, but bounced back with an eagle on the par-5 18th to end one back.
John E. Morgan and Tyrone Mordt, who both shot 68 on Saturday, are tied for seventh place at 13-under-par 203.
World No. 10 Lee Westwood, the highest ranked player in the field, posted his second straight 70 and is tied for 13th at 10-under-par 206.