Els stands at 11-under-par 133. Lee Westwood, who lost to Els in a playoff at this event a year ago, is one shot back. The Englishman posted the low round of the day, a 7-under 65.
Mike Weir (67) and two-time Nedbank winner Bernhard Langer (67) are two shots off the pace at 9-under.
'I wasn't at all sharp on the front nine,' said Els. 'But once again the back nine was totally different. I missed a 12-footer for eagle at the 10th but got the birdie and then birdied 11,12 and 14. I played really well in that stretch.'
His only mistake came on the par-4 15th after a poor drive into the right rough resulted in a bogey.
Westwoods day consisted of seven birdies and no bogeys. He went out in 32, which included a birdie at the par-4 eighth ' a hole that the 12 competitors played in 7-over on Friday.
'I've got my confidence back and I felt like the Lee of old out there again,' said Westwood, who didn't win on the European Tour for the first time since 1995. 'I don't know whether I've been mentally drained this year but I've just been going through the motions.'
Spains Sergio Garcia had a triple-bogey 7 at the eighth. His tee shot went left of the fairway and hit the brick path that runs alongside it. The extra bounce caused his ball to shoot into the rough where, after a lengthy search, it was discovered, though deeply buried.
It took the 21-year-old two shots to find the fringe of the fairway, and two more to reach the green. He did recover, however, birdieing his next two holes en route to a 1-under 71. He is 5-under for the tournament, tied with two-time champion Nick Price for eighth place.
Retief Goosen shot his second successive 68 to finish 36 holes alone in fifth place at 8-under. Hes followed closely by 1996 winner Colin Montgomerie, who carded a 69 to move to 7-under.
Jim Furyk, the lone American vying for the $2 million first-place check, is at 6-under following a 67.
Irishman Padraig Harrington (72) is nine back of Els, while Darren Clarke (68) and Thomas Bjorn (72) are tied for the final position at 1-under.
Clarke played impressively Friday. He rediscovered the strength that had deserted him Thursday because of low blood sugar to shoot 6-under 30 on the back nine at the Gary Player Country Club.