Shane Warne believes Sri Lanka and New Zealand are the two main obstacles to Australia winning a third successive World Cup title.
The veteran leg-spinner, now retired from international cricket, has been buoyed by seeing Ricky Ponting's team recover from defeats to England and New Zealand earlier in the year to put together six wins in a row in the Caribbean.
"I said before the start of the World Cup that Australia - after losing a couple of games, missing five of their top batsmen that weren't playing and still making 350 against New Zealand, even though they lost - just had to sort a few selection issues out and sort a few of their bowlers out," Warne told Sky Sports.
"If they got that I thought they'd go all the way. I didn't think there'd be too many teams that would come close to them. But I think New Zealand Sri Lanka are probably the dangers."
Warne, who is in England preparing for the start of the County Championship season with Hampshire, believes England can still qualify for the last four despite the fact they must win all their games from here on in to do so.
"They've played a lot of one-day cricket and I'm not sure they've got the right side at the moment," Warne added.
"They've got two or three of the top few that haven't even made a hundred in one-day cricket.
"I'm not sure the World Cup is the time to give people experience, it's a time to play your best side and try and win all your games. But the whole world wants to see England playing good cricket.
"Maybe they might just be peaking at the right time. There's some big games coming up. They might win them and sneak into the semis and surprise everyone."
Australia's next match is against Sri Lanka in Grenada on Monday, while England face South Africa on Tuesday in Barbados.