Australia 's preparations for their Ashes defence have taken a hit with captain Pat Cummins struggling with a lower back issue and given no return-to-play timeline.

The 32-year-old fast bowler has been ruled out of upcoming white-ball series against New Zealand and India after scans revealed signs of lumbar bone stress.

Cricket Australia (CA) confirmed on Tuesday that Cummins had lingering back pain from the West Indies tour and the injury would require ongoing management in the lead-up to the five-Test Ashes.

However, selectors chairman George Bailey was upbeat on Cummins' rehabilitation prospects, saying staff expected him to be fit and ready for the series-opener in Perth from November 21.

"There’s plenty of time left -- somewhere in the 80-day range," Bailey said.

"Even i

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