Sun City - Henrik Stenson of Sweden extended his lead to six strokes before lightning stopped play for the day in the second round of the Nedbank Challenge at the Gary Player Country Club on Friday.
Stenson followed his blistering nine-under-par 63 on Thursday by playing the first 10 holes of the second round in three-under.
"I was scrambling a bit more compared to Thursday," he said. "But I am playing well. I am not trying to defend a lead. If I can give myself enough birdie opportunities I can keep moving forward."
Stenson sank a six foot birdie putt on the par-five 11th shortly before play was stopped.
His nearest challenger for the $1.2m first prize, Rory Sabbatini, was two-under for the day but had a birdie putt of a similar length when the siren sounded and the players had to mark their balls and leave the course.
The biggest mover of the day was KJ Choi of South Korea, who was five-under after 13 to move to within one of Sabbatini and six behind Stenson.
Robert Karlsson of Sweden was a further stroke back on a day when eight of the 12-man field played sub-par golf.
Choi had a run of three successive birdies which was halted by the suspension of play.
But the Korean said he was not concerned about having his momentum interrupted. "I take it hole by hole and will go out on Saturday and start again," he said.
Choi, playing Sun City for the first time, said he understood the course better and said he felt relaxed after attending a sponsor's party at an artificial beach, followed by a good night's sleep.
"I started feeling good with my putter," he said. "I sank a few good putts to save par on the first nine and then I started making a few to make birdies."
Conditions were made slightly easier after heavy overnight rain and the rain which followed the suspension of play Friday was likely to make the greens more receptive, according to Stenson.
But Stenson warned that the course would probably play longer because there would not be much run on the fairways, while the rough could become even tougher. "Some of the lies in the rough are horrific," he said. "You have to avoid the rough."
Stenson's only blemish on Friday came at the first hole when he hit his tee shot into thick rough and was well short of the green with his second shot.
Stenson hit straight back with a two-putt birdie at the par-five second, hit a seven-iron to four feet for another birdie at the fifth and pitched to three feet for another birdie at the par-five ninth.
England's Lee Westwood played steady golf to be three-under for the tournament after completing 11 holes but pre-tournament favourite Sergio Garcia, was 10 off the pace after 12 holes.
Defending champion Trevor Immelman seemed out of contention at one-over after playing 13 holes.