Sydney - Mitchell Starc is expected to be out for a "prolonged period" with a back stress fracture in a further blow to Australia's fast bowling stocks, Cricket Australia said on Monday.
Starc returned home earlier this month from Australia's one-day series in England with lower back soreness and CA's worst fears were realised with confirmation of his injury.
"Mitch Starc had scans following his arrival back to Australia and they have shown an early stage low back stress fracture," CA's chief medical officer Justin Paolini said in a statement.
"His management plan will be determined in the coming days but he is expected to be unavailable for a prolonged period."
The left-arm fast medium bowler endured a frustrating tour of England, playing in the first, third and fifth Tests of the five-match Ashes series while being dropped for the second and the fourth.
CA had better news concerning another paceman Jackson Bird, who also returned home early from England with back trouble.
"Jackson returned home with some lower back soreness. We have ruled out a major injury but will review scans in two weeks to confirm this," Paolini said.
"We expect that he will be available during the Ashes (in November)."
Starc joins other Australian fast bowlers James Pattinson and Pat Cummins on the sidelines with back injuries.
Pattinson was diagnosed with a stress fracture in his back after the second Test at Lord's in July, while Cummins is expected to miss most of the 2013-14 domestic season with recurring back trouble.
CA general manager team performance Pat Howard said Starc, Pattinson and Cummins were all under 24 years of age and studies had shown that until fast bowlers get into their mid-20s they are more susceptible to injury.
"Historically, we've rarely seen three such promising young fast bowlers come through at the same time and all of a similar age so when they get injured of course that will be disappointing," Howard said.
"We're doing our best to minimise longer term injuries, but we are also realistic that such injuries are possible.
"Looking at a comparison of some of Australia's best quicks at the age of 23, Pattinson and Starc are second and third on the list behind Craig McDermott in terms of performance.
"What that tells us is we have a greater reliance on younger fast bowlers at international level than ever before and we're getting the most we can out of these talented young players, who are all coming through into international cricket together," Howard said.