He had displayed his skill-set back in his native South Africa on the Sunshine Tour with several tournament victories, but Oosthuizen, who was 27 at the time, had rarely shone in Europe.
His sole success had come in March of that year, when he emerged victorious at the Open de Andalucia de Golf in Spain, winning by three shots to England's Richard Finch.
In the months leading up to the tournament at the Old Course, the Mossel Bay-born player had only registered a best performance of tied-20th at the Welsh Open - hardly form that will put you into Open contention.
But what arrived at the first tee was a man devoid of pressure, a player who could slip under the radar and play his own game. And he did exactly that.
Oosthuizen made a name for himself as early as the first round, recording eight birdies to end the opening day in second position behind early leader Rory McIlroy.
The expectation was that Oosthuizen would slip away amongst the array of top names at the top of the leaderboard, but he did the opposite. At the midway stage, he led the field by five shots. This for a player who had previously only made the cut once at a Major in eight appearances.
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Again, few expected Oosthuizen to canter to the Claret Jug in the manner that he ultimately did. England's Paul Casey and Lee Westwood were in the chasing pack and had the potential to make their move.
Casey did gain two shots back on Oosthuizen during the third round, but the South African still went into Sunday with a four-shot advantage.
The Englishman was still in contention when the duo arrived at the ninth hole, but that's when Oosthuizen made his kick for home, driving the par-four hole to make eagle.
Combined with Casey's triple bogey at the 12th, that was job done for Oosthuizen, who cruised through the final few holes to seal his maiden Major title by seven shots.
On immediate reflection, Oosthuizen told reporters that it would take time for the result to sink in, but it needed to and fast, because his success had catapulted him into the public eye.
However, it became apparent in the aftermath that the triumph would not change Oosthuizen. Three top-10 finishes followed during his final seven tournaments of the year and the South African was soon becoming on the game's rising stars.
Oosthuizen's next opportunity to add another Major came at The Masters in 2012, where, despite an albatross during the final round, he succumbed to Bubba Watson during a playoff.
Despite a relatively poor 2013, Oosthuizen is still ranked number 11 in the official world rankings, and while a neck problem may derail his hopes of a second Open victory in Scotland this week, no-one would be surprised to see the 30-year-old become a multiple Major champion in the future.