SYDNEY - Skipper Graeme Smith thinks South Africa’s test series win in Australia four years ago was a key step on their rise to the number one ranking and another good showing over the next month could be just as important.The 2-1 series win in 2008-09 was a first for the Proteas in nine trips to Australia and although they immediately lost a home series to the men in baggy green caps by the same margin, they have barely looked back since.Unbeaten in a series since that second encounter with the Australians four years ago, the South Africans are certainly not lacking in confidence ahead of a three tests in what has traditionally been one of the more difficult countries to tour."Winning here four years ago, you arrive here knowing it’s something you’ve done before, it certainly helps in the self-belief factor, knowing that you’ve overcome a hurdle before,” Smith told reporters at the team hotel on Monday.