Alex Noren produced a five-under-par 67 on a weather-affected second day of the Nedbank Golf Challenge hosted by Gary Player to lead by two shots at the halfway stage.
The Swede, who has three European Tour wins to his name already this year, carded six birdies and a single bogey on Friday to move to eight under par.
Home favourites George Coetzee, Jaco van Zyl and Louis Oosthuizen are among the chasing pack on six under, alongside Chris Wood and Fabrizio Zanotti.
Beginning the day a single stroke behind overnight co-leaders Felipe Aguilar, Ross Fisher and Jeunghun Wang, Noren fired a birdie at the short fourth to get to four under before play was suspended for one hour and 42 minutes due to threatening lightning.
Noren made a strong start to his back nine when play resumed, making successive gains at the tenth and 11th to get to six under.
After dropping his only shot of the day at the 12th, the 34-year-old bounced back straight away with a birdie at the next.
Noren moved to within one shot of leader Zanotti when he picked up another stroke at the 15th, and when the Paraguayan missed his par putt at the 17th, Noren found himself in a share of the lead on seven under.
And Noren holed his ten-foot birdie putt at the 17th, while Zanotti dropped another shot at the last to see the Swede open up a two-shot lead.
After his second round, Noren said: ‘I made a lot of birdies on the back nine after that delay, which was great fun. I managed to chip-in, which always helps. And then make a birdie on 17, which is quite a tricky hole today. Overall, I’m very pleased.’
Zanotti made the perfect start to his second round, notching back-to-back birdies at the first and second holes to get to four under, before making the first hole-in-one in the tournament’s history – with a seven-iron from 210 yards – at the short fourth to take the lead.
After dropping his first shot of the day at the seventh, Zanotti rolled in his eight-foot birdie putt at the eighth to return to six under.
When play resumed at 15:50 local time, Zanotti fired birdies at the tenth and 14th to move to eight under, but back-to-back bogeys at the 17th and 18th saw him drop into a tie for second.
Speaking about his stunning ace at the fourth, Zanotti said: ‘When people told me that it was the first hole-in-one in the history of the tournament, it sounded strange for me, but then the people from the tournament confirmed it to me.
‘It was very strange, but lucky for me, I’m the first one. I think it was just a perfect club, a perfect distance for me with a seven-iron. The wind was helping a little, so the ball, it was going to release a little.
Meanwhile Denmark’s Lasse Jensen produced a sensational albatross at the long 14th on his way to a second-round 69 which saw him move to two under.