Paul Peterson fired a brilliant bogey-free 62 to open up a two-shot lead as the rain began to fall again on day one at Royal Johannesburg and Kensington Golf Club.
Torrential rain had soaked the course through much of the week, leading to the cancellation of Tuesday's Pro-Am, but sterling work from the ground staff meant that the course was in good condition for the start of play.
American Peterson was among those to take advantage of the dry conditions, moving to nine under on the West Course before the heavens opened again in South Africa.
Peterson has enjoyed a steady start to the season as he looks to follow up a 2016 campaign that brought him a first European Tour victory at the D+D REAL Czech Masters
He went out and came back in 31 on Thursday to sit two shots ahead of English pair Aaron Rai and Paul Waring - both playing the East Course that will be used for the full field after the cut - with a spot at The Open Championship available to the top three players in the top ten at the end of the week who are not exempt.
Peterson made a blistering start with birdies on the first, second, fifth, sixth and ninth to turn at five under. He holed from eight feet on the 14th for another birdie before taking advantage of the par five next and putting his tee-shot on the par three 16th to three feet.
A closing birdie then put the icing on the cake as the 28 year old set an intimidating target.
With the East Course generally regarded as the tougher of the two layouts being used this week, both Rai and Waring could be pleased with their day's work.
Rai set the early pace from just the second group out, birdieing the first, fifth, sixth and eighth to turn in 33. Another birdie followed on the 14th before an excellent curling right-to-lefter on the next and a birdie on the last saw him hit the front.
Waring was even more impressive on the front nine, making birdies on the first, fourth, fifth, sixth and eighth and while he took his tally of gains to nine on the way in, he also recorded two bogeys.
Swede Sebastian Soderberg was then at six under with a single bogey in his 66 on the East, while Frenchman Romain Langasque fired a 65 on the par 71 West, with an eagle on the ninth.
Home trio Dean Burmester, Dylan Frittelli and Teaghan Gauche, and Italian Francesco Laporta were then all at five under, a shot clear of English pair Paul Maddy and Jordan Smith, Frenchman Damien Perrier and Scot Marc Warren.
