Shane Warne [Images] is in doubt for Australia's [Images] second Test against West Indies [Images] starting in Hobart on Thursday because of back pain.

Pace bowler Stuart Clark joined the squad on Wednesday as a precaution although he is unlikely to play even if Warne, acclaimed as the greatest spin bowler of all time, were to be ruled out.

A Cricket Australia spokesman told Australian Associated Press that Warne had never suffered back pain before but received some treatment after experiencing some problems at training.

Australia delayed the announcement of their team until just before Thursday's toss with captain Ricky Ponting [Images] telling journalists either leg-spinner Stuart MacGill or left-arm paceman Nathan Bracken [Images] would serve as 12th man.

Both would be expected to play if Warne was ruled out.