SYDNEY (AFP) - Australia are bracing for a battle to regain the Ashes for the first time in six years but injuries, selection woes and a questionable build-up give every sign of a team in upheaval.

The signs are not promising in the home camp as Michael Clarke's men try to stop old rivals England from winning a fourth successive Ashes series.

The last time England made the long trip to Australia, in 2010-11, the series ended in humiliation for the hosts who lost three Tests by an innings to capitulate 3-1.

Injuries have already put the Australians on the back foot with front-line pace bowlers Mitchell Starc, James Pattinson and Jackson Bird all out with back problems.

Skipper Clarke is battling a chronic disc injury, placing a question mark over the ability of Australia's only genuine world-class batsman to last the series.

In the recent Tests in England, Australia's top six were changed so frequently that ex-skipper Ricky Ponting urged selectors to "pick and stick" with young batsmen such as Usman Khawaja and Phil Hughes.

And in a move that highlights the hosts' edginess, Cricket Australia said it will not reveal any injuries - unless a player has been ruled out of a Test - to avoid giving a possible advantage to England.

As difficulties abound, criticism has been flowing freely and former selector Merv Hughes this week hit out at Australia's pre-Ashes schedule.

While England are preparing on Australian pitches in Perth, the hosts - albeit minus several key players - are in the middle of a seven-game one-day series in India.

"I am just dumbfounded with England being in town and preparing for an Ashes that starts in about a month's time and Australia has got a team playing in India, playing in subcontinent conditions preparing for the Ashes," said the former Test fast bowler.