Having seen a three-shot overnight lead cut to one as Branden Grace made a charge, Oosthuizen engaged a gear the others simply don't have to add his name to an illustrious roll-of-honour.

Birdies at the fourth, sixth, seventh and ninth gave the former Open champion a cushion, before a sumptuous approach to three feet set up an eagle at the 14th to all but confirm the outcome of the tournament.

Now unleashing his full repertoire, Oosthuizen fired another one close at 16 for birdie and while dropping a shot at the 17th, he was able to enjoy the walk up 18 on his first start in the event since 2010.

Overcome with emotion on the 18th green, Oosthuizen was barely able to speak. "It was nice to do it for them (the crowd). I've been through some stuff with injuries but... great family and friends (were) always with me."

As Grace's challenge faltered, a closing bogey seeing him not only drop out of the top three but miss the chance to seal his place in next year's Open field, it was Romain Langasque who cut through the pack to take second place.

The Frenchman picked up four shots in three holes from the 12th to briefly get within three of Oosthuizen, but his focus was on sealing an Open debut as one of the three highest finishers not already exempt. The former amateur star did so with a brave par putt at the difficult 18th.

Earlier, Bryce Easton had also holed an excellent par save for a closing 66 and a share of third, but the two final Open spots instead went to Oliver Wilson and Charl Schwartzel by virtue of their higher world rankings.

Wilson is without full status on the European Tour but took advantage of this rare opportunity with a final-round 67, while Schwartzel recovered from a double-bogey at the 13th - his second of the round - to deny Thomas Aiken a place at Portrush.

Aiken had been on course for solo third at worst before a three-putt bogey at the 17th was followed by a closing par. Even then, he would have joined Langasque and Wilson but for Schwartzel's birdie at the 17th which, after a four at the last, saw him join the share of third place and effectively eliminate Aiken.

Madalitso Muthiya, the highest-ranked Zambian in the sport at 1330 in the Official World Golf Rankings, threatened to conjure a fairytale finish with birdies at the 14th and 15th holes, but he needed one more at 18 for an Open place and instead made bogey.

Former SA Open winner Brandon Stone closed with a round of 66 to finish in a tie for seventh with several others, including Grace and close friend Haydn Porteous, but England's Matt Wallace endured a nightmare day to fall outside the top 10.

Day three report

Louis Oosthuizen will take a three-shot lead into the final round of the South African Open after firing a battling 67 on day three in Johannesburg.

The 2010 Open champion entered the weekend two shots behind fellow South African Charl Schwartzel but the 2011 Masters winner will now have to do the chasing after a disappointing 72.

Oosthuizen moved to 14 under at Randpark Golf Club, with England's Matt Wallace and Zambian world number 1,330 Madalitso Muthiya at 11 under alongside Schwartzel.

Oosthuizen holed a long putt for birdie on the first and capitalised on the par-five fourth before handing the shot straight back on the next.

An excellent approach into the sixth helped him turn in 33 and he completed a hat-trick of birdies on par fives as he got up and down from bunkers on the 12th and 14th before birdieing the par-three 15th from 15 feet for a four-shot lead.

A bogey after finding sand off the tee at the par-three 17th removed some of the gloss but Oosthuizen was pleased with his day's work.

"It was tough again but I played well," he told europeantour.com. "Eighteen more holes of good golf and I just need to take one shot at a time."

Schwartzel recovered from bogeys on the first and third with a birdie on the 12th, while Wallace carded a 68 as he looks for a fourth win of 2018.

Muthiya overcame two double-bogeys in a level-par 71, with Scot Robert McIntyre and four-time Major champion Ernie Els then in a group of eight players six shots off the lead.

Day two report

Charl Schwartzel will take a one-shot lead into the weekend after firing an excellent bogey-free 63 on day two of the South African Open.

The 2011 Masters champion is looking for a first win since 2016 and made six birdies and a spectacular eagle over the Bushwillow Course at Randpark Golf Club to get to 12 under.

Zambian Madalitso Muthiya was at 11 under, a shot clear of 2010 Open champion Louis Oosthuizen, fellow South African Zander Lombard and America's Kurt Kitayama.

Birdies at the first and fifth helped Schwartzel turn in 33 and he was edging into contention after further gains on the 11th, 12th and 14th.

A long putt on the 16th had him within one of the lead and despite having to lay up on the 17th after a poor tee-shot, he spun his third into the cup on the par five for an eagle.

The South African has six top fives without a victory at his home open and was refusing to get carried away after seeing some recent good form fail to yield a victory.

"I still can't figure out why I'm not getting the performances I need, even after that round," he told europeantour.com.

"I've had a few tournaments where I've played well like this, so I'm not going to talk too much yet.

"There's lots of golf to play. All I know is I'm playing well. I'm driving the ball well and I haven't been doing that consistently."

Muthiya carded a 68 on the Firethorn Course, a score matched by Lombard on the Bushwillow. Kitayama registered a 69 on the Bushwillow, with Oosthuizen battling to a 70 on the Firethorn.

England's Matt Wallace was playing alongside Oosthuizen and he signed for a 69 to sit at eight under.

Day one latest

Former Open champion Louis Oosthuizen moved ominously into the lead on day one of the SA Open in Johannesburg.

Playing the easier Bushwillow layout, one of two used to accommodate a field 240 players over the first 36 holes, Oosthuizen carded nine birdies in a round of 62, one short of the course record carded by Shubhankar Sharma a year ago.

Birdies at the first, fifth and seven made for a solid yet unspectacular outward nine, before the 36-year-old came alive at the turn with three in a row from the 10th and further birdies at holes 14, 16 and 17.

It's Oosthuizen's first appearance in his national championship since 2010, when he finished third having won the Claret Jug at St Andrews earlier in the year, and on what his 11th start in the event he'll be strongly fancied by many to finally win it.

"It was beautiful, the greens were very good and receptive, you wouldn't say that it was dry," said Oosthuizen, following reports that the course was firm following a hot spell without the usual rain in South Africa's largest city.

"Foot on the gas the whole time, you know there are so many good golfers. I just need to play well; it's been a long time since I had a win, everything is trending in the right direction and I like where (my game) is at the moment."

Earlier, Ernie Els had signed for an opening 66 at the same course, a round matched Branden Grace as the big names in the field took advantage of ideal scoring conditions.

Matt Wallace birdied the 17th before scrambling a par at the last to go a shot lower, his six-under 65 enough for second place of those who teed off in the morning before Tyrone Ferreira joined him there.

Max Schmitt was first to post a low number at Firethorn, which played considerably tougher, with the German making just one mistake in a round of 66 to sit alongside Els and company on five-under.

Among the late starters, Kurt Kitayama showed no signs of a hangover from his breakthrough win in Mauritius last week, four birdies in the opening five holes firing him straight into contention once more.

The American had to be patient thereafter and was rewarded with an eagle at the par-five 14th to move to six-under, and further birdies at the 15th and 18th holes saw him card an excellent 63 at the tougher Firethorn.

That was enough to share second with Zambia's Madalitso Muthiya, whose round came at Bushwillow and includes five birdies in his opening six holes, with Zander Lombard (Firethorn) a shot further back in fourth.