South African Wilco Nienaber opened up a one-shot lead heading into the final round as he looked to become the youngest ever winner of the Joburg Open.
The 20-year-old entered day three a shot behind Jacques Blaauw but, as his countryman dropped back, Nienaber carded a 67 to get to 16 under par, a shot clear of Dane Joachim B Hansen.
England's Richard Bland carded a 68 to sit in a tie for third at 11 under, alongside Blaauw and two more South Africans in Shaun Norris and Brandon Stone.
John Caldwell is the only Irish representative in the field - he carded a 71 on Saturday to sit in a tie for 44th.
Nienaber, who leads the European Tour in driving distance this season at an average of 337 yards, only turned professional last year and could claim a first win in just his 23rd appearance, while Hansen, 10 years his senior, has 145 appearances under his belt without a victory.
"It felt like a struggle to be honest," Nienaber told europeantour.com. "But around the turn I holed a few crucial putts which really kept the momentum going and from there I just kept going. I'm pleased with the round.
"It's going to be great. It's going to be the first time that I'm in that situation and I'm just going to embrace it and enjoy the day."
Hansen holed an 18-foot putt on the par five fourth for an eagle and added birdies on the fifth, sixth, eighth and ninth to turn in 29 and lead by two.
A dropped shot on the 11th stalled his momentum and Nienaber took control as he recovered from a slow start with a gain on the ninth and a hat-trick of birdies from the 12th.
It looked like he could establish a commanding lead, but Hansen birdied the 14th and last to card a 64 and keep right in touch.
Bland, 47, has played 466 events without a victory and he sandwiched birdies on the fourth, fifth, ninth, 10th and 14th with dropped shots on the third and 18th.