Smith and Ntini celebrate South Africa's series win

South Africa have overtaken Australia as the leading one-day side after a series win against Pakistan and Australia's slump in form.

"Of course it's nice to be number one and it is a reward for our good form.

"But at the World Cup, it is necessary to maintain your best for more than a month," Smith said.

South Africa and Australia will clash in the group stages on 24 March.

Having comprehensively beaten India and Pakistan in home series, and seen Australia lose to England and New Zealand, the South Africans are highly fancied to win that game.

"It is dangerous to predict you'll win the World Cup, but we are confident," said Smith, whose team failed to reach the Super Six stage when they hosted the tournament four years ago.

"Previous South African teams may have allowed too many expectations to be created but I don't think it's going to happen this time," he added.

The skipper also believes Australia's current losing run will not last long.

"They have match-winners such as Ricky Ponting and Adam Gilchrist who still have to return and will make a big difference. Their main problem is injuries and the way they solve that will probably determine their fate."