Trevor Fisher Jr carded a superb nine-under-par 63 to move into a two-shot lead after three rounds of the Africa Open.
Fisher Jr started Saturday's play four shots adrift of overnight leader Matt Ford, but a bogey-free round that included seven birdies and an eagle at the par-five third saw him wrest the initiative at the East London Golf Club.
If Fisher Jr can hold his nerve in Sunday's final round he will continue South African dominance at the tournament, with a player from the country winning the event on all five occasions it has been hosted on the European Tour.
Having gone out in 33, including his eagle effort, Fisher Jr turned the screw on the way home with five birdies in his last eight holes and he lies on 16 under par for the tournament.
Englishman Ford started his round in positive fashion as he went three under through the opening seven holes.
However, Ford found himself in trouble at the eighth - eventually slumping to a double-bogey six.
Ford recovered with three birdies in four holes between the 10th and 13th, but another dropped shot at 14 left him at two off the pace on 14 under.
Jaco van Zyl, runner-up at the Joburg Open last week, sits in outright third thanks to a four-under 68.
Denmark's Morten Orum Madsen fired himself into contention after signing for a terrific round of eight under par, a bogey at the ninth his only blip.
Madsen is now among a cluster of four players who are six shots adrift on 10 under for the tournament.