So Garcia, who won at Sun City in 2001 and 2003, finished with a one-under-par 71, inching him to nine-under-par overall, with Louis Oosthuizen closing in, a brilliant 67 on Friday leaving South Africa's highest-ranked golfer (39) just one shot behind.
Four-time major victor Rory McIlroy, who needs a top-two finish to stay in with a chance of winning the Race to Dubai, is 10 shots off the pace on level par, after a one-over 73.
Mikko Korhonen (70) was third at 6 under, two behind Oosthuizen and three off the lead.
Cape Town - Erik van Rooyen has dreamed of playing in the Nedbank Golf Challenge since he was a child, and he gets his chance on the back of a year of solid performances in his debut season on the European Tour.
Li Haotong, who can also win the Race to Dubai at next week's Tour Championship, carded a 71.
A spectacular 18th where the ball circled the hole and rolled back out for a bogey summed up a frustrated round for Garcia.
He is four shots ahead of the field.
The Dubliner felt his back go as he practised at Lumine Golf Club in Tarragona yesterday and may not be able to join Tramore's Robin Dawson and Ardglass' Cormac Sharvin at the Lakes Course for today's first round of the six-round race to finish in the top 25 and ties. "It's not ideal to see three-putts, but some of the pins were nearly impossible to get to and when you leave yourself 20 or 25 feet putting over hills then it's gonna happen sometimes", a phlegmatic Garcia said after his round on Friday.
"I didn't play great in China but I've had a week off and just sort of reflecting on things".
Frittelli carded a five-under on Friday‚ and is in a group that includes England's Lee Westwood and Aaron Rai‚ as well as Ireland's Shane Lowry.
"After eight I had a good run at a few holes".
Ross Fisher came close to the round of the day when he made the turn in 31 after three birdies and an eagle in his first nine.
Garcia's error-free round was in stark contrast to that of world number six McIlroy, whose level-par 72 was characterised by some wayward driving. He then found trees again and lost his ball.
He also birdied the first two holes and ended with a tally of seven birdies, offset by bogeys on two of the four par-threes.