Matthew Hayden is a doubt for Australia's ICC World Twenty20 opener against Zimbabwe on Wednesday.
The World Cup's top run-scorer suffered with back spasms during one of Australia's warm-up matches against New Zealand.
He joins all-rounder Shane Watson (strained hamstring) and batsman Michael Clarke (lower abdominal strain) as real concerns for the Group B opener.
The news is the latest setback for the three-time world champions, after captain Ricky Ponting's departure for the tournament was delayed because of a family illness.
An eight-wicket defeat to hosts South Africa in a friendly on Sunday was not ideal preparation, although new coach Tim Nielsen remains confident.
"It's normal early season stuff at the moment," Nielsen said. "The fact that we have had some competitive hit-outs have been beneficial from a skill point of view.
"Physically at the moment it is taking a bit of time to get up and going.
"But Hayden's been flat on his back overnight, and the physio is doing a great job."
The 35-year-old left-hander plundered 659 runs at an average of 73.22 in the Caribbean earlier this year and would be a big loss.
Clarke also contributed 436 runs to the cause, averaging 87.2 per innings, and Nielsen admits there is a big question mark over his participation as well.
"He's getting better, all the signs are that he's improving, and again it's just a management thing and seeing how he goes," Nielsen added.
"We're hopeful he'll be playing during the week, either Wednesday or Friday against England."
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