Louis Oosthuizen wins World Golf Champions event in South Africa . Successfully defends title in Durban . Birdies four og the last four holes to beat qualifier Branden Grace . Grace won British Open at St Andrews in 2010 .
Louis Oosthuizen wins Volvo Golf Champions event in South Africa . Successfully defends title in Durban . Birdies four og the last six holes to pip compatriot Branden Grace . Oosthuizen won British Open at St Andrews in 2010 .