Shane Warne has dismissed South Africa's chances of winning the World Cup, insisting New Zealand and Sri Lanka pose a bigger threat to Australia's title defence.

The retired spinner said South Africa, who recently replaced Australia as the world's number one ranked team in one-day cricket, lack the flair required to win the championship in the Caribbean, starting on March 13.

"I don't think South Africa are a chance," Warne told the Australian Associated Press on Friday.

"They're very regimented. I know they're rated the number one side in the world at the moment but I don't think they're the best side in the world."

Warne, who was named man of the match in Australia's 1999 World Cup win over Pakistan, said New Zealand and Sri Lanka loom as the biggest dangers to Australia's bid to win an unprecedented third straight title.

"I just like the way they play," he said.

"I reckon they're a chance with the small grounds and the way the wickets will play. I'm sure they'll be a very good chance."

Australia were overwhelming favourites to win the tournament a month ago before suddenly losing five games in a row but Warne was confident Ricky Ponting's men would rediscover their form when it mattered. 

"I don't have any doubts whatsoever about the Australian side. They'll be fine," Warne said.

"It's just a little bit of a hiccup. If they can sort a few little issues out and get their team right -- the one they want in terms of selections -- get their bowling right in the middle periods and in the end I'm sure they'll be fine."