South Korea's Wang Jeunghun will take a three-shot lead into the final round of the Nedbank Golf Challenge after a stunning third-round 64 at Sun City.
Meanwhile, Pádraig Harrington couldn’t find any form as he shot another 75 to sit well back on 10 over par.
Wang was just 20 when he became the youngest player in European Tour history to win consecutive events earlier this season after victories in the Hassan Trophy and the AfrAsia Bank Mauritius Open.
And the 21-year-old has a third win firmly in his sights after defying a swirling wind to card six birdies and an eagle at the Gary Player Country Club to finish 11 under par.
The world number 91 birdied the first, second, fourth and sixth to reach the turn in 32 before a brilliant approach to the par-five 10th set up an eagle from just three feet.
Further birdies on the 11th and 18th gave Wang a three-shot lead over former Open champion Louis Oosthuizen, who had drawn level on the 16th but then three-putted the last two holes.
“I hit it really well today,” Wang said. “I played really good and I’m really happy to have made this far. It was a fantastic round for me.
“I saw my shot on the 10th on the leaderboard screens and it was really lucky. The ball hit the rough twice and then kicked right and almost hit the hole. I had a lucky day today.
“I don’t want to think about a win right now. I just want to focus on the last 18 holes and just try to do the same as today.”
Oosthuizen was annoyed by his poor finish, adding: “I would have been a lot calmer right now if I was one behind instead of three, but I played nicely.
“I can’t really look at what happened on the last two greens. I got the pace on both of the first putts wrong. It’s not nice finishing like that, but I’m hitting it well so I’m looking forward to tomorrow.”
England's Andy Sullivan, who was playing alongside Wang, is four shots off the pace after an excellent 68, with Branden Grace and overnight leader Alex Noren on five under after rounds of 71 and 75 respectively.
Race to Dubai leader Henrik Stenson finished his round in style with birdies on the 17th and 18th, a second 69 of the week leaving the Open champion on four under.
The 40-year-old can win the Race to Dubai with a victory this week if nearest rival Danny Willett finishes outside the top 10, but the Masters champion carded a much-needed 67 to get back to level par for the tournament and into a tie for 16th.
“As everyone knows it’s been a tricky few weeks,” Willett told Sky Sports 4. “Today the head was in a better place and we scored better around a golf course we know well, put it in better positions where you can score from even if you don’t hit great shots.
“Obviously Henrik’s still played some good golf, but it was nice not to fall too far back. A good day tomorrow and hopefully we can stay on his tail.
“I withdrew from the World Cup yesterday due to the back possibly not holding up and maybe that’s eased you off, knowing you now just have to concentrate on these things.
“Tomorrow will be a pretty big day. We’re too far off the lead, but certainly not too far off having a really nice finish if we can get another low score in.”
Stenson, who has a lead of more than 250,000 points over Willett, said: “It was a tricky day out there. I didn’t play my best by any means. I had to fight hard and got back into it on the back nine with a couple of good shots.
“I’m just trying to have a good week. My goal was always to come into the last one and have it in my own hands and no matter what happens here tomorrow I will have that, so I have to play some good golf newt week to wrap it up.”
