London: Australia captain Michael Clarke is a doubt for their opening Champions Trophy match against England on Saturday due to an on-going back problem, Cricket Australia said on Tuesday.
Clarke sat out their final warm-up game against India in Cardiff on Tuesday after missing last Saturday's match against West Indies.
"Michael is still experiencing some lower back pain and as such is not fit for the warm-up game against India today," said Cricket Australia physiotherapist Alex Kountouris in a statement.
"Michael will head to London tomorrow for specialist treatment and a decision on his fitness for the next game will be made in due course."
The absence of Clarke would be a boost for England, who have concerns over bowlers Stuart Broad and Steve Finn, while bludgeoning batsman Kevin Pietersen has already been ruled out.
Australia's stand-in 50 overs captain is 30-year-old George Bailey, their Twenty20 skipper, who led them to a comfortable victory over West Indies.