Oosthuizen compiled a final-round six-under 66 to overtake Scotsman Scott Jamieson, who began the fourth round with a five-stroke lead, in the European Tour event at Durban Country Club on Sunday.

In the process, Oosthuizen improved his world ranking to fourth, with Irishman Rory McIlroy holding a comfortable margin at the top of the ratings.

The South African, who won the 2010 British Open, said he would focus on the  year’s four Majors in his attempt to climb further up the global list.

“It’s a great start. Somehow I manage to win the first ones of the season,” Oosthuizen said.

“But, top spot, you know, is a tough one to get. I think Rory is far ahead at the moment.

“If I can somehow get to number two, then I can set my sights on number one.”

Oosthuizen believed it would take a spectacular season for anyone to catch the 23-year-old McIlroy.

“He’s obviously in a great spot in his life and in his swing as well. He’s far ahead of number two.

“Even if I or Tiger (Woods) or Luke (Donald) play really well, Rory is still  playing as well. It will be tough to catch him, but it’s going to come down to the Majors.

“If somehow I can try and get a Major this year, or two even, that’s where the difference is going to be -- the Majors.”

Oosthuizen had not yet given much thought to his approach for the year’s first Major -- the Masters at Augusta in April.

He came agonisingly close last year to donning the green jacket as he lost to American Bubba Watson in a playoff.

“I'm playing (the course) the week before and I'm going to the tournament later, but I'm just going to try see it as any normal tournament,” he said.

“I never like to have big expectations before the tournament. I love to start the tournament and then if I feel my game is there, and I'm playing really well, everything starts rolling.

“My biggest thing is to get my game ready, so I feel I've got a good chance for the week.”