Not wanting to give a poor display - and fearing he might after failing to break par in the curtain-raising pro-am - Oosthuizen scored a five under 67 to share the lead with Richard Green and Dustin Johnson after the first round of the Nordea Scandinavian Masters at Bro Hof.
The 27 year old South African, a runaway seven shot winner at The Home of Golf on Sunday, admits he is looking forward to going home next week, but it might be with another title under his belt.
Only Australian left-hander Green and American Johnson - the player who led the US Open Championship before a closing 82 last month - could match his opening effort.
"I had a good sleep, but I woke up tired again and the win has definitely drained me," said Oosthuizen. "But the crowds were unbelievable, cheering me onto every green and every tee.
"I wanted to play nicely. The last thing I wanted was to put on a bad show and it was important not to think too much about next week."
Leader for the last three rounds in Scotland, The Claret Jug holder kicked off with a birdie, followed with eight pars and then came home in a superb 32.
That even included a trip to the water - there is plenty of it at the spectacular new European Tour course - on the long 13th, but he came back from a six there with birdies at the next two and finished in style with a 30 footer for another.
Johnson was three ahead of Graeme McDowell with a round to go at Pebble Beach, but a dream day for the Northern Irishman was a nightmare one for the 26 year old.
He triple-bogeyed the second hole, doubled the third and in the end finished eighth.
Last week was an eventful one for Johnson too - if he had repeated the birdie-birdie finish to his third round on Sunday he would have tied Lee Westwood for second place.
Instead he took a double bogey six on the Road Hole 17th, then missed the widest fairway in golf on the last and went out of bounds. That dropped him to 14th, but he remains on course for a Ryder Cup debut in October.
He said: "I hit the ball beautifully all day and was never in trouble at any point."
Green, seeking his third European Tour title, made up for two bogeys with no fewer than seven birdies after changing to a driver brought out to him by a friend.
Among those only a shot behind are Korean KJ Choi and Barclays Scottish Open champion Edoardo Molinari, who with a top two finish on Sunday could climb into an automatic qualifying spot on Europe's Ryder Cup table.
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