Australia captain Michael Clarke has been ruled out of his side's second Champions Trophy group match against New Zealand on Wednesday.
Clarke, 32, has been struggling with a lower back injury and missed the opening 48-run defeat by England.
Cricket Australia physiotherapist Alex Kountouris said: "Michael is continuing to have intensive treatment in London.
"While he is making good progress, he has not improved sufficiently enough to play the game against New Zealand."
Clarke missed Australia's last two warm-up matches because of the long-standing problem, which also forced him home in March from a 4-0 series defeat against India.
Last Thursday, Australia coach Mickey Arthur told BBC Sport he remained confident Clarke would be fit for the Ashes.
He said: "I am concerned but confident we will have him firing somewhere in this tournament for us and then into the Ashes."
The Champions Trophy is a one-day international tournament featuring eight teams that runs between 6 and 23 June. The first Test of the five-match Ashes series begins at Trent Bridge on 10 July.