That meant two-shot swing as Oosthuizen, who stood on the final tee with a four-shot deficit, ended the penultimate round just two shots behind, his level-par 72 leaving him on eight-under-par overall, while Garcia's one-under 71 lifted him to 10-under-par.
Garcia's two Nedbank titles came in 2001 and 2003, and his 64 was his lowest round at the tournament for 17 years. The 45-year-old Englishman hadn't won anywhere for more than three years.
"It's a tournament I've always wanted to play as a kid, and I came here plenty of times with the family to watch", van Rooyen said. "You're never sure whether you're going to be able to do it again. And I feel like my game is really right on the verge".
Jutanugarn finished second on seven under and Boutier, ranked 150th in the world, was third, a further shot back, after shooting a sparkling six-under-par 66.
Bunkered greenside at the treacherous par-four 17th, he didn't get his recovery on to the green and then compounded his error by clumsily chipping seven feet past and missing the bogey putt. His birdies on Nos.
Fisher had eagled the second and picked up six more birdies to reduce Garcia's lead to two shots. "I'm going to see if I can shoot below 70 and see if that's good enough".
Barkley expecting hostile reception from Everton fans
The former Real Madrid star netted twice in the Blues 3-1 victory against Crystal Palace last weekend. It was a very hard day for me. "But I know very well that strikers want to score".
"But today showed I have still got it mentally, it was a great performance".
Korhonen parred the 18th for a one-under 71, leaving him three off the pace alongside Westwood, who mixed five birdies with two bogeys from the sixth to the 14th in his three-under 69.
Oosthuizen could easily have gone into the final round with a four-stroke deficit but for Garcia sending his second shot out of the 18th hole rough into a grandstand.
Oosthuizen looked to be struggling after a double-bogey on the eighth saw him turn at one under-par for the round. Westwood didn't drop a shot all day.
"I have to play really well this week to give myself a chance, even half a chance going into next week, and that's what I'm going to try and do", said McIlroy, who is eighth in the Race to Dubai, nearly two million points behind Molinari.
Rory McIlroy is a man on a mission at the Nedbank Golf Challenge this week as he looks to mount a late charge for a fourth Race to Dubai title.