Graeme Storm fired a course-record equalling 63 to take a two-shot lead into the third round of the BMW SA Open hosted by City of Ekurhuleni.
The Englishman was bogey-free at Glendower Golf Club as he got to 12 under to lead the way from South African duo Trevor Fisher Jnr and Jbe Kruger, and American Peter Uihlein.
Rory McIlroy had threatened to snatch the headlines on the back nine as he picked up eight shots in as many holes from the eighth courtesy of eight one putts to get within a single shot of the lead.
A bogey-bogey finish stalled his momentum, however, and the World Number Two was nine under after two rounds alongside English pair Laurie Canter and Jordan L Smith, South African Keith Horne and Scot David Drysdale.
Storm agonisingly missed out on retaining his playing privileges by just 100 euros last season but was then handed a reprieve when Patrick Reed missed the Final Series and did not make his requirement of events.
A tie for fourth at the Alfred Dunhill Championship was an excellent start to the season and he continued his fine form in South Africa, where he recorded a career-low score of 62 at the 2013 Joburg Open.
Storm got off to a flying start with birdies on the tenth, 11th and 12th and when he holed a lengthy putt on the 18th, he had a share of the lead for the first time.
It was nip and tuck at the top with Storm, playing partner Kruger, Smith and Horne all sharing the lead at one point but Storm was relentless, birdieing the first and third and when Kruger dropped a shot on the fourth, the door was open.
The putter was hot, it was hot yesterday and it was hot today - Graeme Storm
Storm barged through it, putting his approach to the fifth inside six feet and then holing a curling 20-footer on the next before making another gain on the eighth.
"It's obviously great to shoot a score like that," he said. "I had a putt on the last, it was a long putt to equal my best-ever score.
"The putter was hot, it was hot yesterday and it was hot today. Yesterday I didn't capitalise as much as I did today.
"I could have birdied a couple more of the par fives, I only birdied one of them today. So to shoot 63 and only having birdied one of the par fives around here, you know, I've played pretty well.
"I tip Rory to win this week because he hits it miles and he hits it straight. If I keep on his tail, I'll be happy."
McIlroy had slipped nine shots off the lead after four holes with a bogey and a double but an eagle on the eighth sparked a run of peerless iron play, helped along by the fact he did not miss a putt for eight holes before his disappointing finish.
Uihlein had a single bogey in a brilliant 64 as he played the front nine in 30 with three closing birdies, while Kruger also had a big finish with an eagle on the eighth in his 67.
Fisher came into the day as the joint overnight leader and he recorded five birdies and a single bogey in a 68.
Drysdale was bogey-free with an eagle on the eighth in his 65, Canter picked up four shots in his last four holes in a 66, Smith signed for a 68 and Horne - who was the other man sharing the overnight lead - posted a 69.
Jaco Van Zyl was then at eight under after a 65 that included the second hole-in-one of the season on the 17th.
The home favourite holed a four iron from 223 yards that was always bang on line and took two hops before rolling into the cup, winning him a BMW i8.
Play was suspended in the afternoon due to the threat of lightning but when it resumed on Saturday morning, Frenchman Romain Langasque joined Van Zyl on eight under after notching a birdie at the last to complete a second-round 66.
