18 July 2010 11:50 GMT

When the third round of the 150th Anniversary Open Championship finally drew to an end, the giant scoreboard that towers high above the grandstands surrounding the most famous 18th hole in golf showed that one man alone headed the field.

It wasn’t as many might have expected — the pre-tournament favourite Tiger Woods, and it wasn’t Phil Mickleson, another player highly fancied to collect the famous Claret Jug at the end of play today. Neither was it one of the star names of the European Tour, such as former Open Champion, Padriag Harrington, 2010 European Order of Merit winner, Lee Westwood, American-based Paul Casey or Europe’s new and brightest rising star, Rory McIlroy.

Some of these illustrious names are featuring high on the leaderboard, but along with the rest of the field, they too ended the day lagging behind the Championship leader, Louis Oosthuizen. And while the little-known South African’s 15 under par score for the first three rounds may not have threatened to eclipse previous 54 hole totals from previous Championships, it did give the 27 year-old, from Mossel Bay in South Afirca, a welcome, if certainly not unassailable four stroke advantage over his nearest rival.

Oosthuizen’s record in his three previous Open Championship appearances reveal that he has played in three and missed the cut on each occasion: a statistic that will not be lost on those closest to him on the leaderboard going into today’s final round.

In addition, the South African has also missed the cut in both the 2010 US Open and US PGA. Yet while his previous performances in the majors has certainly been nothing to write home about, it’s worth remembering that he’s obviously a good enough player to have qualified to compete in the majors.

Opening rounds of 65 and 67 had given Oosthuizen the halfway lead in the Championship and this put him under the microscope for the first time in the week, with regard to discovering if he was made of the stuff required to cope with the pressures of leading the Open Championship.

Would he crumble and drop back into the pack, as so many have done in the past? Not only did Oosthuizen answer that question in the most emphatic way possible, by producing an almost flawless display of superb, controlled golf. But by the end of the day he had also secured a four shot lead over the field and in the process probably put paid to the Championship aspirations of many of the more fancied and more experienced players in the field.

Crumble under pressure? If anything the South African seemed to be thriving on the cut and thrust of the occasion. And as he remarked after completing his third round by driving the 18th green as two-putting for the easiest of birdies; “My first birdie on seven just got me going, really. I felt like I swung it really well all day and probably left a few birdies out there, but 69, I’m really happy.”

Looking forward to the final round, where he will be partnered by his nearest challenger, Paul Casey, Oosthuizen said; “It’s not every day you play in the final group leading The Open Championship. You know, I think by going out there and just enjoying the moment and not thinking about everything else, it’s just going to make the day really nice.”

The most likely candidates among the players who will be aiming to spoil Oosthuizen’ day are his closest rivals, Paul Casey (-11) and the trio of Martin Kaymer (-8), Henrik Stenson (-7) and Lee Westwood (-7). All proven winners and all equally desperately keen to add The Open Championship trophy to the impressive haul of silver wear which they have already acquired.

If the leader turns out to a scoreboard watcher, one name he will certainly be looking for during the final round is that of Rory McIlroy. After his disaster in round two, McIIroy clawed his way back into the Championship with a gritty third round performance that has left him on four under par. And as he said after his third round; “I know what I’m capable of around the course and I know what I’m capable of in final rounds.”

Further back in the chasing pack, waiting hopefully for any slip up from the leader, are a list of proven winners that include the likes of Retief Goosen (-5) and Robert Karlsson (4) along with the American pair of Dustin Johnson (-5) and Nick Watney (-7). As for pre-tournament favorites, Tiger Woods and Phil Mickleson, while both men are more than capable of producing spectacularly low scores, it will take something exceptionally special if either man is to get remotely close enough to the leader to cause any concern.

Can Louis Oosthuizen continue to produce the high quality golf he as so far played and go on to win The Open Championship? Or will his dream slowly dissolve and disappear under the weight of his own expectations, in what looks certain to be tough and exciting day packed with drama, and played out over the ancient links of the Old Course?

In March this year Oosthuizen recorded his first victory on the European Tour, when he won the Open de Andalucia. And that victory will hopefully stand the South African in good stead when it comes to coping with the pressures of leading the Championship during the last round.

Winning a tour event is no mean feat. The question is, does Louis Oosthuizen have both the golf game and the steely nerve that will be required if he is to hold off his challengers and win the world’s oldest and greatest Championship? Only time and the golfing gods can tell.