Louis de Jager posted a 64 to take the first-round lead at the Tshwane Open but had three European Tour winners breathing down his neck at Pretoria Country Club.
The 30 year old was bogey-free in getting to seven under on a day of good scoring and opened up a narrow advantage over fellow South African Thomas Aiken, Chilean Felipe Aguilar and America's Julian Suri - who have six European Tour victories between them.
Home duo Shaun Norris and Combrinck Smit were then at five under, one ahead of a large group three shots off the lead.
De Jager's best European Tour result came at the inaugural Tshwane Open where he finished third in 2013, and he also finished fourth at the AfrAsia Bank Mauritius Open in December.
"It is a very nice start," he said. "It is nice to go off in the morning and then post a score like that.
"I am very happy with my game. I have been working quite hard on the game so it is nice to see some good results over the last few months.
"For us South Africans this is big, they are all important. Everybody knows without you having to even talk about it and everybody knows what they are playing for. So it just motivates you more."
The 30 year old birdied the 11th, 16th, 17th and 18th but five pars in a row meant he looked to be settling into the chasing pack.
A 15-foot putt on the sixth then moved him to five under before he hit a smart tee-shot into the eighth and got on the ninth green in two, getting down in the same amount of strokes to lead the way.
Aiken opened with a bogey but then made five birdies in a row from the 11th and when he added another on the 18th, he was out in front on his own.
For us South Africans this is big - Louis de Jager
Playing partner Suri had birdied the 12th, 13th and 15th and he made another on the second before holing a slippery ten-foot right-to-lefter on the third to join the lead.
Aiken - a three-time winner on the European Tour - went a long way left off the 14th tee to drop a shot but bounced back with a 25-foot birdie on the par three next and Norris soon joined the lead.
He had made birdies on the 11th, 12th, 17th and 18th but a double-bogey on the first had threatened to derail his progress.
The 35 year old bounced back with gains on the second and third and an approach to three feet on the sixth had him in a share.
American Suri went over the back of the seventh to concede a bogey and while he bounced back with a 20-footer on the next, that was only enough for a share of second as Norris put his tee-shot to six feet.
The leader then hit a ragged tee-shot on the ninth to drop a shot and he was leapfrogged by Aiken and Suri, who both took advantage of the par five.
Aguilar regained his card at the Qualifying School in November for an 11th consecutive season on Tour and was the best of the later starters.
The two-time winner birdied the 11th and then made four in a row from the 16th before dropping a shot on the second. A monster putt on the eighth then got him to five under before he took advantage of the last.
Smit turned in 33 with birdies on the fifth and seventh and while he bogeyed the tenth he hit back with a birdie on the next and an eagle on the 12th. A second dropped shot of the day came on the 16th but he had a birdie-birdie finish.
There were then 17 players at four under including 2015 champion George Coetzee.
