Selectors named a 13-man squad with Shaun Marsh, Ed Cowan and Ben Hilfenhaus included, but there was no place for injured allrounder Shane Watson and fast bowler Ryan Harris.

Chief selector John Inverarity said the size of the squad was due to the continuing uncertainty about the fitness of Marsh, who has been troubled by a back complaint.

"Phillip Hughes and Usman Khawaja have been omitted from the Australian team that played against New Zealand in Hobart and Marsh, Ed Cowan and Ben Hilfenhaus have been added to the squad," Inverarity said.

"Shane Watson was not considered for selection as he has not recovered sufficiently from his (hamstring/calf) injury, while Ryan Harris has not yet achieved the volume of bowling required to be available for consideration for Test selection."

Cowan was included on the strength of his 109 against India playing for a Chairman's XI in Canberra on Tuesday along with two centuries in this season's domestic Sheffield Shield and one for Australia A against the touring New Zealanders.

"Ed Cowan has been in excellent form in recent weeks," Inverarity said.

"His inclusion is in recognition of his consistently good performances and we anticipate that he can provide steadiness at the top of the order.

"Ben Hilfenhaus has regained form this season and he provides a strong and reliable bowling option."

Inverarity said Hughes and Khawaja both needed to produce "compelling performances" to be considered for future Test selection.

"We see both Phillip Hughes and Usman Khawaja as developing players with bright futures and remaining as players of significance," he said.

"They are determined young men and I know that they will work hard to produce compelling performances and push strongly for further consideration."

The Australian squad assembles in Melbourne from Thursday ahead of the Boxing Day Test start.

Australia: Michael Clarke (capt), Brad Haddin (vice-capt), Dan Christian, Ed Cowan, Ben Hilfenhaus, Michael Hussey, Nathan Lyon, Shaun Marsh, James Pattinson, Ricky Ponting, Peter Siddle, Mitchell Starc, David Warner.