Bernd Wiesberger birdied the last in an opening 67 to take a one-shot lead into the second round of the Nedbank Golf Challenge hosted by Gary Player.
An elite field has gathered at Gary Player Country Club for the seventh Rolex Series event of the season and at one point seven of them shared the lead at the top of a congested leaderboard in Sun City.
A stunning approach to the 18th saw Wiesberger get to five under and break out of the pack as he goes in search of his second win in an incredibly consistent season.
The Austrian has missed just three cuts in 24 events and sits 12th in the Race to Dubai Rankings presented by Rolex, partly thanks to his victory at the Shenzhen International in April.
That was his fourth European Tour win, with his third having come at the 2015 Alstom Open de France, and a triumph this week would seriously boost his chances of making his Ryder Cup debut at Le Golf National next year.
Home favourite Branden Grace was a shot behind Wiesberger with Frenchman Victor Dubuisson, Scotland's Scott Jamieson and American Julian Suri all alongside him at four under.
Defending champion Alex Noren, South African Charl Schwartzel, England's Graeme Storm and Japan's Hideto Tanihara were then at three under.
A win for Tommy Fleetwood this week would wrap up the Race to Dubai title but his opening 73 left him six shots off the lead.
Wiesberger bogeyed the fifth but responded with back-to-back birdies before another dropped shot on the ninth saw him turn in 36. He started the back nine with a hat-trick of gains and after dropping a shot on the 13th, birdied the next, chipped in on the 16th and finished with a flourish.
"It wasn't easy to be honest," he said. "It was quite breezy, quite steady direction-wise but still the course is quite tricky off the tees. You want to get a lot of fairways to be able to attack the flags and that's quite challenging when there's gusty winds.
"But I played all right. I've not had great success when I was here last time but I approached it with a neutral mind and I played a lot better than I have the last couple of weeks and putted good. Took a couple of chances so that was nice, to get out there kind of relaxed and just let it happen."
Dubuisson was out in the first group of the day and it looked for a long time that his target of four under was going to be enough to lead the way into Friday. He had birdies on the 13th, 14th and 18th with a dropped shot on the 16th as he turned in 34 but made back-to-back gains on the first and second.
Grace bogeyed the third and fourth but made gains on the seventh, tenth and 13th before holing from the fringe on the next for an eagle and picking up another shot on the 15th.
Playing partners Suri and Jamieson started on the back nine, with the Made In Denmark champion making birdies on the tenth, second, seventh and ninth in a bogey-free effort.
Jamieson made three birdies on each side but dropped shots on the 11th and 18th.
Swede Noren chipped in for an eagle on the tenth and made birdies on the second and third but dropped a shot after a sloppy approach to the 17th.
Schwartzel made a bogey on the last after gains on the ninth, 12th, 14th and 16th, while Tanihara made five birdies and two bogeys in his 69.
Storm already has a win in South Africa this season at the BMW SA Open hosted by City of Ekurhuleni and he had an eagle and a double-bogey in his roller coaster of a round.
There were then 12 players in the group at two under.