Bupa Support Team Head Coach Darren Lehmann has been diagnosed with Deep Venous Thrombosis and will miss the upcoming KFC T20 INTL series against India.
Lehmann will spend the next few days in hospital and not fly to Adelaide with the rest of the team on Sunday for the first T20 on Tuesday.
Cricket Australia's Chief Medical Officer Dr John Orchard said the condition was very treatable but as it is unwise to fly when dealing with the condition, Lehmann will stay in Sydney.
Batting coach Michael Di Venuto will take over as interim coach for the T20 series.
"It's more a scare than something to worry about, but it will require him to have a bit of an absence because we'll be playing it safe," Dr Orchard said.
"It's a condition that's got a very good outcome if you get it early, which we have.
"So it's all good news, but one of the factors associated with is it's unwise to fly until you have stabilised the condition.
"So he will be absent from the Australian team camp for a short period.
"And that will depend on how long that will take for him to get stabilised and treated so they're happy to release him.
"He'll only be in hospital for a day or two but he will be unavailable to fly and then we'll re-assess how it's all going.
"He's very sensible about it and wants to put his health first so he's happy to hand over the reins to make sure he's going to be OK from a health perspective, which is what we expect.
"Symptomatically he's OK. He could coach, but we're not going to have him flying around ... that's the main thing that he can't do is fly."
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Deep Venous Thrombosis (or DVT) is a clotting of blood, predominantly in the legs.
Dr Orchard was unable to give an extact timeframe on when Lehmann will be able to return, but said a rough timeframe would be a matter of weeks. He could not confirm whether or not Lehmann would be available for the upcoming tour of New Zealand.
Lehmann experienced DVT back in 2007 when he was still a player and Dr Orchard said the current condition is far less serious than what he's experienced previously.
Lehmann experienced swelling in his left calf in the hours before the final Victoria Bitter ODI against India on Saturday and was taken to the radiology clinic at the Sydney Cricket Ground for scans.
On having the diagnosis confirmed, Lehmann was admitted to the Royal Prince Alfred Hospital for observation overnight during India's run chase.
Lehmann's wife Andrea was notified and the Australian players were told at the end of the match, which they lost by six wickets.
Executive General Manager of Team Performance at Cricket Australia Pat Howard confirmed Di Venuto's appointment as interim coach and wished Lehmann a quick recovery.
"Our first thoughts and concerns are obviously with Darren and his family – health is more important than any cricket match," Howard said.
"Everyone at Cricket Australia wishes him a speedy recovery.
"We plan for all eventualities and on that basis Michael Di Venuto, who has previously coached Australia A in 2014, will step up to fill Darren’s role as Head Coach for the KFC Twenty20 International Series.
"We will assess the situation on the basis of medical advice and with Darren’s best interests in mind over the coming days."