The 36-year-old, who had a three-shot advantage at the start of the day, appeared to have buckled under the final-round pressure as he made consecutive bogeys on holes 2 and 3.

However, he recovered by sinking four birdies before making the turn and subsequently cruised to a four-shot victory on an 18-under-par 266 total at the Randpark Golf Club.

The South African Open hosted by the City of Joburg is the third Asian Tour title won by Oosthuizen. He was victorious at the 2012 Maybank Malaysian Open and the 2016 Perth International, which was also his last professional win.

“My wife and kids have been phenomenal. It would’ve been great to have them here with me.” – Louis Oosthuizen

“It’s always tough when you’ve been through some stuff and the people who have been behind you are not here to celebrate with you,” said the 2010 Open champion, who was struggling to contain his tears.

“My wife and kids have been phenomenal. It would’ve been great to have them here with me.”

He added: “My putting has been as good as it’s ever been. I had all the confidence to hit my putts, even if I hit them two or three-feet past. You don’t have that all the weeks, but this week I definitely had that.”

Oosthuizen earned a winner's cheque of US$203,335.

Frenchman Romain Lanagasque grabbed second place after carding the day's lowest score of 66.

As the tournament is part of The Open Qualifying Series for the 148th Open at Royal Portrush, Lanagasque has earned a spot at the major tournament next year together with Schwartzel and England's Oliver Wilson.

RIGHT: Oosthuizen was wiping away tears after winning his national Open at the weekend. PHOTO: Stuart Franklin/Getty Images.

Tour member Yikeun Chang displayed his championship credentials by finishing commendably in tied-seventh against an elite field.

After making a double bogey at the first hole, the Korean made amends with a birdie-eagle on 3 and 4. He made three more birdies and another bogey before ending his tournament with a 68.

Jbe Kruger excelled at his national Open as he carded a 70 to grab a share of seventh place. This is the South African's first top-10 finish in 2018, and his first since October last year.

Kurt Kitayama (70) of the United States, who won his maiden Asian Tour title last week in Mauritius, finished in tied-15th with fellow Tour members Jarin Todd (68), Matt Wallace (74), as well as Asian Tour Honourary Member and International Ambassador Ernie Els (71).

David Gleeson was the best of the Australians with his share of 65th place.