The 27-year-old was six under par and leads from Lee Westwood, who hit a second successive round of 70, and home hope Darren Fichardt, both two shots back.
Westwood hit six birdies as the field battled to deal with the windy conditions but also dropped shots on four of the holes.
"It was tricky and sometime just confusing with the wind picking up and dropping all day. There is little margin for error. But I was driving well and you can attack the flags if you do well down the fairways," Westwood said after his round.
Fichardt, who only got a call to compete in the 60-man field on the morning of the opening day when Anthony Wall withdrew, hit a second round 69 as he birdied all of the par-five holes. His two round total is 140.
Overnight leader Bernd Wiesberger of Austria double-bogeyed the fourth hole and then slumped dramatically as he fell six shots behind after a second round 77.
(Reporting by Mark Gleeson; Editing by Christian Radnedge)
