The Somerset fast bowler has been a major selection doubt since contracting a back spasm during England's crushing defeat in the second Test in Adelaide.

The injury-ravaged tourists are already without batsman John Crawley, who was ruled out on Thursday with a hip injury.

Caddick, meanwhile, bowled during Thursday's net session at the Waca but coach Duncan Fletcher said he would not name him unless he was convinced he would not break down again.

"Caddick is still going through a bit of a trial and we want to see how he reacts," he said.

"It's encouraging by what we saw of him this morning, but that can be misleading and that's a decision we have to make - we have to make sure there aren't any niggles arising as he cools down.

"We may even want to see him have another bowl in the morning before the Test before we make our decision."

Should Caddick, who has taken 220 wickets in 60 Test appearances, fail to prove his fitness, Matthew Hoggard will keep his place in the side.

The Yorkshireman had looked destined for the axe after taking just one wicket in the series to date.

Durham's Steve Harmison is the only bowling certainty for the Perth Test and is likely to be joined in the starting line-up by Surrey's Alex Tudor.

Fletcher insisted he still had no idea what his bowling attack would be less than 24 hours before the third Test.