For the day, the 44-year-old carded a 4-under 68, which puts his total score for 36 holes at 11-under-par 133. He maintains a one-stroke margin over the rest of the field, eight players of which will have to complete their second rounds early Saturday morning.
The bad news for Vaughan, however, is that just behind him, in second place at 10-under, is Northern Ireland's Darren Clarke. Clarke also managed to complete his round Friday, as he chalked up a new course record of 63 at the Gary Player Country Club.
With his experience, and with the final two rounds of this tournament to be conducted over this same Gary Player course, the big Ulsterman has got to be the favorite entering the weekend.
'That's just the way it goes,' he commented after his round. 'When I play well, I play really well.'
Indeed he does. This is the man who has become notorious for his streaky play. When he's off, he may play horrendously, as he did at last week's South African Open, when he missed the cut with rounds of 77-78.
But when he is on, he can beat anyone, as he did against World No. 1 Tiger Woods at last year's WGC World Match Play Championship.
This week, it seems Clarke may have found his form again. And when asked of the prospect of shooting 62 Friday, Clarke responded: 'I was thinking about it all the time.'
Vaughan is not one to give in so easily, however. He proved this on Friday, after coming in on his final nine holes in 3-under 33, which included an eagle at the par-5 7th (his 16th hole of the day).
'I scrambled a couple of holes,' Vaughan said. 'It was a bit tricky because there was just enough of a wind to always keep you on your guard.'
One player who wasn't exactly on his guard Friday was local Graeme Francis. Playing the par-3 13th hole at Lost City, he put his tee shot into a notorious crocodile pit just off the green.
Unaware of a local rule which permits play from the area, the South African jumped into the pit (seeing there were no reptiles in its vicinity) and proceeded to play his ball out.
He could do no better than a bogey on the hole, but was later informed that he was to be disqualified for playing the shot.
The incident may well have been the classic case of all risk, no reward.