Robert Rock leads the South African Airways Open but has Irishman Darren Clarke hot on his heels at the Pearl Valley Golf Estates.

Englishman Rock was one of only four players to shoot under par on a gusty day in Paarl, with a South African trio of Charles Schwartzel, Alex Haindl and Ulrich van den Berg on one under.

After his 33rd place finish at the Alfred Dunhill Championship last week, Clarke is level par having carded four birdies and four bogies.

"As I said earlier this week, I am playing really nice and I did the same again today," Clarke said. "I played really good all day, but threw away a couple coming home just like I did last week. But overall I am playing really nicely.

"The course is really tough, especially in the wind this morning. It could die down some time this afternoon and then some players could make a move, but then again it could blow. Time will tell."

However, Clarke's fellow Ulsterman Rory McIlroy faces an uphill challenge if he is to make it to day four after a disappointing 83 saw him card at least a bogey on 12 holes.

Peter Lawrie is two over after a 74, while Colm Moriarty is nine over after an 81.

Former world number one Greg Norman was one-under par after 11 holes but slipped back to three over thanks to four dropped shots between 13 and 16.

Defending champion Ernie Els and US Open champion Angel Cabrera were two of the big names to suffer in the windy conditions.

Els endured a torrid time as he carded a five-over par round of 77, including two double bogeys, while Cabrera was on the same score with six holes still to play.

Earlier this morning two-time winner Trevor Immelman was forced to withdraw after just two holes.

The 27-year-old complained of a rib problem that affected his breathing.