Warne said he expected Australia to overcome their recent slump of five straight one-day international losses to win a third consecutive World Cup in the Caribbean.
"I think New Zealand and Sri Lanka are two of the danger sides," the world's leading Test cricket wicket-taker said.
"I just like the way they play. 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," he said.
"But I don't have any doubts whatsoever about the Australian side. They'll be fine," said Warne, speaking in Adelaide.
"They've still been making 350, so if they keep making those sort of scores I'm sure they'll be okay.
"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."
Warne predicted the West Indies will rise to the occasion, while rubbishing the chances of the Proteas.
"The West Indies always seem to do well in these sorts of tournaments and the ICC Champions Trophy, so they're a bit of an outside hope. It's their home country too, so they'll play better there.
"But I don't think South Africa are a chance.
"They don't have much flair. 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 retired in January having taken a world record 708 wickets in 145 Test matches.