Paul Lawrie emerged as the midway leader of the Nedbank Golf Challenge on Friday after another day of tough scoring at the Gary Player Country Club.

Lawrie shot a three-under-par 69 in the second round to move to four-under overall, a one-stroke lead over Germany's Martin Kaymer, who matched the Scotsman's 69 -- the best two rounds of the day.

South Africans Charl Schwartzel and Louis Oosthuizen were two strokes further back, in a tie for third on one under par with Italy's Francesco Molinari and American Bill Haas.

On a day in which the golfers continued to be agitated by a swirling wind and thick semi-rough, it was the consistent if conservative play of Lawrie and Kaymer that brought the greatest reward.

Lawrie played beautifully in the tough conditions, his only dropped shot coming on the par-four 15th, and the 43-year-old was understandably content with his position halfway through the $5 million (R44 million) tournament.

"I played nicely again. I struggled with the driver so I hit quite a few three-woods, which was a strong club for me today," Lawrie said.

"I gave myself chances and I putted a lot better today.

"This course is demanding off the tee and you've got to be in play if you hope to go for the pins. It's important to drive well, as it's pretty tough out there.

"The wind is swirling, chopping and changing, and it's difficult to get your distance right."

With no one able to conquer Sun City's famed course, the leaderboard was bunched and Kaymer said the weekend shootout was an appetizing prospect.

"There are eight golfers within five shots, so that's quite nice," Kaymer said.

"If you play good and a few putts drop, then you can shoot five or six-under, so nobody can relax."

Schwartzel struggled to find his best game but kept himself in contention by shooting a 71 that left him on one under par.

Oosthuizen joined him half-an-hour later with a birdie on the 18th hole, while Haas needed an inward nine of just 33 shots to also finish in the tie for third.

Haas was the joint overnight leader with fellow NGC rookie Nicolas Colsaerts, but they both discovered why a debutant has not won at Sun City since Mark McNulty in 1986.

Colsaerts, who shot a 70 on the first day, made a disastrous start to Friday's second round with a double-bogey seven on the second hole and a triple-bogey at the par-four third, finishing with a 78 and a tie for 10th on four over par, eight shots off the pace.

Haas double-bogeyed the first and dropped further shots at the seventh and ninth holes, before fighting back well.