As Australia's selectors prepare to name their preliminary squad for this year's World Cup, Jason Gillespie has warned that his fellow countrymen cannot be written off after a recent resurgence in form.

Having lost their previous four ODI series since the start of last year, twice to England and once each to South Africa and India, Australia came back from 2-0 down to win their five-match series in India last month.

Australia then won 5-0 against an under-strength Pakistan, who opted to rest six front-line players ahead of the World Cup, putting them on an eight-match winning streak going into the opening match of their title defence against Afghanistan in Bristol on June 1.

"Every other team in this World Cup knows that Australia know how to win World Cups," Gillespie told ESPNcricinfo. "That is something that will be in every other country's mind, that Australia - while they might not be seen as favourites - they know how to win World Cups.

"So for me, I think Australia are very much a dark horse and I wouldn't write them off, that's for sure."

Australia, whose selectors convened on Tuesday, are now No.5 on the ICC world ODI team rankings, behind No.1 and favourites England, India, New Zealand and South Africa.

However, Gillespie - the former Australian fast bowler, now Sussex coach - believes five-time champions Australia are "peaking at the right time".

"They'll take a lot of confidence going into this World Cup," Gillespie said. "Of course I want to see Australia do well. They've copped a lot of stick in recent times but in the last couple of series in India and Pakistan, they've shown some real promise and they've played some really, really good cricket."

Australia have unveiled their kit for the World Cup, a predominantly yellow outfit with lime-green trim, and are set to name their 15-man squad on April 15, although they can make changes up until May 23.

Having made wholesale changes - several times - during the past year, the Australian line-up is by no means clear-cut.

One key question mark hangs over who will make way for David Warner and Steve Smith, who are both expected to return, having served their ball-tampering bans. Usman Khawaja, who averaged 76.60 in India and 54.40 against Pakistan last month, may need to drop to No.3 to allow Warner to open with Aaron Finch.

Shaun Marsh and Peter Handscomb are arguably battling for one place while Ashton Turner is expected to miss out, despite being highly rated by some on the selection panel.

Another conundrum is presented by the race for fitness of injured fast-bowling trio Mitchell Starc, Josh Hazlewood and Jhye Richardson.

Meanwhile, apart from their two series victories against Australia, England have, since January 2018, suffered a shock six-run defeat at the hands of Scotland in a stand-alone match, defeated India 2-1 at home and Sri Lanka 3-1 away before drawing their most recent series against West Indies in the Caribbean 2-2 with one match washed out.

Gillespie, who played just four group matches before returning home injured from Australia's successful 2003 World Cup campaign, believes England, the hosts, are rightful favourites this year.

"There's been a lot of talk of England being favourites and playing at home and I certainly think they deserve that tag," he said. "They've played some wonderful 50-over cricket. They've been really innovative and shown a lot of aggression with bat and ball, they've been really dynamic in the field.

"I think it will just be managing the expectations in England. Personally, selfishly, I'd love to see an England - Australia final at Lord's. I think it would be an amazing spectacle."