Overnight leader Henrik Stenson suffered the embarrassment of a complete air shot in the early stages of Saturday's third round of the Nedbank Golf Challenge at Sun City.
Stenson had already seen his one-shot lead wiped out by playing partner Jaco Van Zyl's opening birdie when he attempted a delicate flop shot from just off the second green, only for his club to slide straight under the ball.
The world number seven was more successful with his second attempt, chipping to five feet and holing for par, but saw Van Zyl - whose superb approach to the first had left him a tap-in birdie - two-putt from long range on the par five for another birdie.
At 12 under par, debutant Van Zyl was one shot ahead of 2008 champion Stenson, with American Robert Streb and Australia's Marc Leishman another shot behind.
Danny Willett's title defence looked to be effectively over as he followed a birdie on the second with dropped shots on the fourth and eighth to fall back to one under par.
Willett, whose victory 12 months ago helped him finish second behind Rory McIlroy on the 2015 Race to Dubai, had been badly hampered by a back injury in a second round of 75 after an opening 67.