Ernie Els, a three-time winner of this event, posted a 4-under 68 to climb into second place at 10-under-par 206. Els is playing for just the second time since injuring his knee in late July.
Charl Schwartzel, the defending champion, moved into a tie for third with a 2-under 70. He was joined at 9-under-par 207 by Louis Oosthuizen (71). Jaco Van Zyl is one stroke further back at minus-8 after a third-round 69.
The tournament is back on track as the second and third rounds were completed on Saturday. Action was delayed Thursday for over two hours causing things to be pushed back. Sunday will have players teeing off split tees with the threat of more bad weather Sunday afternoon.
Oosthuizen was the early leader with an eagle and two birdies over the first six holes at Leopard Creek Country Club. However, he fell off the pace as he played the final 12 holes in plus-3.
Van den Berg birdied the par-5 second to get going. He stuck his approach within 3 feet at the third for another birdie.
The South African tripped to a bogey on the par-3 fifth, but quickly erased that mistake. Van den Berg eagled the short par-4 sixth to jump to minus-8.
Van den Berg kept rolling around the turn with a birdie on No. 10. He knocked his approach inside three feet to setup birdie on the par-3 12th.
The 30-year-old made it two in a row as he rolled in a 5-foot birdie effort on 13 and that birdie gave him the out-right lead. Van den Berg two-putted the par-5 15th for birdie to get to 12 under. He parred his final three holes to remain there.
Van den Berg will go for his first win on Sunday. If he is successful, he will be the seventh straight first-time winner at this event.
'It's going to be a tough day,' Van den Berg said of Sunday. 'But I've been working hard for this. I've been killing myself in the gym one hour a day six days a week. I've also been through a bit of personal drama and everything feels like it's falling into place now. But I can't worry about Ernie or think about all that comes with a win. I've just got to go about my business.'
Els parred his first seven holes before dropping a shot at the eighth to slide to minus-five. The back nine was a different story though. He birdied the 10th and 12th to start making his move up the leaderboard.
The 36-year-old birdied the 15th to get to 8 under. Els finished his round with an eagle on the par-5 closing hole to end at minus-10.
'I was putting terribly at the Nedbank Golf Challenge last week,' Els said. 'This week, I've just been trying to feel my way back into the putting and trying everything. It came together on those last five holes and hopefully I can keep the rhythm going.'
Keith Horne matched the low round of the day with his 7-under 65. That moved him into a sixth place tie at 7-under-par 209. He was joined there by Titch Moore (73), Christian L. Nilsson (70), Doug McGuigan (72) and Alan Michell (71). Phillip Archer, Mattias Eliasson, Sean Farrell and James Kingston are one stroke further back at minus-6.
Second-round leader Michiel Bothma struggled to a 4-over 76. Bothma, who was battling a bout of the flu on Friday, carded one birdie, one bogey and three double bogeys to drop to 3-under-par 213.