Ernie Els and Trevor Immelman have combined for five wins in this event and were two of four co-leaders after the first round. On Friday, they both shot rounds of 6-under 66 and are tied for second place at minus-11.
Retief Goosen overcame an 11 on the 17th hole Thursday to shoot a 3-under 69. On Friday, he eagled the same hole en route to a 6-under 66 and a tie for fourth place. Andrew Raitt, the third first-round co-leader, managed a 4-under 68 and joined Goosen at 9-under-par 135.
Sjoland collected his first birdie of the round at the par-3 third hole, then birdied three in a row from the fifth. He tallied his fifth birdie of the front nine at the ninth, a hole he birdied on Thursday, to make the turn at 9 under par.
The Swede dropped a shot at the 10th, then rattled off four pars in a row. Sjoland birdied four in a row from the 15th to move into sole possession of the lead.
Now Sjoland will be in quite a group on Saturday as he joins Els and Immelman, both ranked in the top-13 in the world and both hometowners with five wins in this event.
'I'll probably be a bit nervous, but this is what we play for,' said Sjoland, 'I'm just going to go out and enjoy it and hopefully I can hit a few good shots and make some putts.'
Sjoland lost his European Tour playing card last year, but hard work has gotten him back in a position to win. He captured the 1998 Italian Open, then added the 2000 Irish Open.
'I got the enjoyment back in my game,' admitted Sjoland. 'I had been on tour for 10 years before that and I was tired of the travelling and being away from my family. So it was good to lose my card and have some time to think.'
Els, a three-time major winner, was 3 under par on his round until he chipped in for eagle at the par-4 16th. He added a birdie at 17 to reach 11 under par.
'We all know she isn't showing her teeth yet and we've been quite lucky,' said Els. 'I felt I could've done better on the front nine, but I kept my patience and started making some birdies on the back nine. The eagle on 16 was a nice bonus.'
Immelman was 2 under at the turn, but added a birdie at No. 14. That sparked a great run, which included an eagle and two more birdies, but the wheels came off at the last. He bogeyed the hole to fall back into a tie with Els.
'I was amazed how well I scored for the way I played,' said Immelman. 'I was fighting my game all day. After the birdie on the first I lost my swing and rhythm, and it was a real grind for me.'
Louis Oosthuizen (65), Steve van Vuuren (65), Jaco Van Zyl (65), Fredrik Andersson (67) and last week's third-pace finisher at the Alfred Dunhill Championship, Lee Westwood (68) are knotted in sixth place at 8-under-par 136.
The 36-hole cut fell at even-par 144 and last week's winner Alvaro Quiros missed the weekend by a single stroke.