While coach Darren Lehmann is confident international cricket has not seen the last of Clarke, he admitted Australia could not afford to take the 33-year-old into the World Cup unless he was 100 per cent fit.

Specialists were analysing scans of Clarke's right hamstring in Melbourne on Sunday, but the captain's fatalistic outlook in the aftermath of Australia's first-Test win at Adelaide Oval, where he had to be driven through the underground carpark to the post-match press conference because he was hobbling so badly, showed the injury is serious.

Australia's first warm-up game for the World Cup is against India on February 8, and their first proper game against England at the MCG on February 14 - eight weeks away.

Australia have to name their 15-man squad by January 7, with George Bailey poised to take the reins if Clarke can't.

Clarke hasn't completed a one-day match since last summer and has played just five of Australia's 18 ODIs this year.

He broke down in Zimbabwe in August and in Perth last month, both times while batting, and missed the ODI series in the UAE. Clarke's mobility in the field is also an issue in the shorter format. It was a regulation bend to field a ball that caused his hamstring to tear on the fifth day in Adelaide, where he sustained a "significant" back injury earlier in the Test.

"He knows he has to be fully fit for one-day cricket," Lehmann said. "One-day cricket is an explosive game and we need guys fully fit all the time.

"He was magnificent in this Test match and he has been magnificent the last few weeks with what's happened with our team and what has happened with Phillip [Hughes] and his family.

"He needs to get it right. He knows that, we know that."

Most worryingly for Clarke, physiotherapist Alex Kountouris has said previously that even with an extended recovery time his injuries can flare up at any moment.

Under International Cricket Council rules, the selectors could replace Clarke from outside the World Cup squad if he sustained a tournament-ending injury. If they wanted him to return later in the tournament, they could only replace him from within the 15. There is a third scenario, which happened when Mike Hussey was ruled out of the 2011 World Cup with a hamstring injury but had a miraculous recovery and was recalled at the expense of another injured player.

Clarke's admission that his career was in doubt took Australian officials by surprise and came after an emotionally draining month in which he has dealt with the death of Hughes and multiple   physical setbacks.

Lehmann would concede only that he was gone for the rest of the Test series against India.

"I think he will be back. You have your fingers crossed, " Lehmann said.

"It will be a case of wait and see with the experts. It will be a case of getting ready for Brisbane with a short turnaround of three days. It was an outstanding Test match, India were fantastic as well. But we have to move on reasonably quickly and get prepared for life without the captain for the next few Test matches."

It was in discussing his World Cup prospects that Clarke dropped the bombshell about his future.

"I don't know exactly how long I'm going to be out for. I think the World Cup, our first practice game is eight weeks away, I'd love to take part in the tri-series, I'd love to take part in the World Cup but I just have to wait and see," he said.

"There's no doubt there's certainly a chance, well there's a chance I may never play again. I hope that's not the case and I'll be doing everything in my power to get back out on the park but I have to be realistic as well."