"Six under any day is pretty good," the 2001 and 2004 U.S. Open champion said. "It was nice to finish off good, too. I'm feeling good. I'm going after the ball a little bit now so getting some consistency going."
Now 44, Goosen hasn't won a tournament since March 2009.
Charl Schwartzel, fresh off a victory in China on the OneAsia Tour last month, had five birdies and no drops in his 67, while Attie Schwartzel carded seven birdies and two bogeys.
South African Christiaan Basson set the early pace, adding four birdies and an eagle to a string of pars in a 66. Crespi and Kruger overtook that, with both players on fire in their opening nines to pick up four straight birdies from No. 12 through 15 and move a shot ahead.
Nixon jumped into the lead at the very end, though, after opening with four birdies in his first five holes and then finishing as strongly with an eagle on the par-5 No. 8, his 17th.
Former British Open champion David Duval was 2 over after opening with a 74. Europe Ryder Cup captain Paul McGinley was 3 over.
The new tour schedule teed off in the eastern suburbs of South Africa's biggest city just four days after Henrik Stenson won the 2013 European money list and season-ending World Tour Championship in Dubai.