The pair were a shot clear of world number 12 Ernie Els and Charl Schwartzel after their 65s, while Englishman David Dixon was in a group of six players a further shot back on six under.
Amongst them was Spaniard Carlos Del Moral with the rest – Richard Sterne, Jaco Ahlers, Garth Mulroy and Tyrone van Aswegen – all South African.
10 others, including Open champion Oosthuizen, David Drysdale from Scotland and England’s Richard McEvoy, were on five under following a low-scoring day at the Durban Country Club, which was effectively day one after organisers abandoned play yesterday less than two and a half hours after the start because the constant rain made conditions unplayable.
Round two, weather permitting, is now scheduled for today and organisers plan a cut to 50 as they bid to squeeze in 36 holes tomorrow.
Two-time former champion Goosen came into the day having already completed four holes on Thursday, but despite his success, he endured a mixed day with two bogeys coming in alongside a pair of eagles and six birdies.
Speaking afterwards, he said: “Obviously, that’s the way you want to start. It went nicely for me yesterday, those four holes in the rain when I managed to get two birdies and then on the first this morning I got another one to keep the momentum going.
“I’m off to a good start so hopefully I can try and start building on this tomorrow afternoon. Then we’ll see what happens on Sunday if we play 36 or 18.”
Cejka, a four-time winner on the European Tour, went through his round faultless with his eight birdies split across both nines.
“It was a good day,” he said. “The practice rounds were not so good for me, but today was excellent.
“There’s still three rounds to go, which is a long, long way. Hopefully I can play well in the next three days.”
Four-time winner Els, who is the highest ranked player in the field, has had an up and down year – his last Tour victory coming back in March – but aims to build on his effort today.
“I missed quite a few putts on the front nine and was getting a little annoyed with myself, but I played a really solid back nine,” added Els, who came home in 31.
“You know I just hit the ball really nicely and that’s something I can take out of today.
“ I really feel like I’m solid from tee to green and you need to be on this course.“Hopefully that back nine will give me a lot of confidence for the weekend.”