A fitness cloud is hanging over Australia skipper Michael Clarke ahead of next month's tour against Pakistan after he re-aggravated his hamstring injury, adding to concern about his durability ahead of next year's 2015 ICC Cricket World Cup and Ashes series.

Clarke is flying home from Harare for scans and assessment after suffering further damage as he starred with the bat when making his injury-delayed return in his team's ODI tri-series loss to Zimbabwe.

Coach Darren Lehmann admitted later the injury-prone skipper may have to be managed even more carefully in future.

Quick Single: Lehmann fumes after shock defeat

Even if Clarke recovers in time for the one-dayers and Tests against Pakistan to be played in the United Arab Emirates, his inability to shake what started as a left hamstring twinge 10 days ago is cause for concern.

It illustrates the increased challenges the 33-year-old is facing just to stay on the park after a career battling chronic back trouble.

Clarke was determined to get back on the pitch but his enthusiasm backfired when he pulled up in pain during his unbeaten innings of 68 in the three-wicket upset defeat in Harare.

While acknowledging Clarke's fitness would need to be closely monitored, Lehmann indicated the selectors had no thoughts of resting their leader and most valuable player through periods of cricket over the next 12 months provided he's fit.

"We have to be smarter with his management maybe," said Lehmann.

"But if your captain's fit he should play.

"That's where we sit as a selection panel.

"He was good to go (against Zimbabwe).

"Now it's about getting right for the next tour."

Even low grade hamstring tears require at least three weeks on the sidelines, and with Australia to depart for the UAE in late September, Clarke will be racing the clock from the moment he touches down.

"I'll listen to the experts," said Clarke, who was embarrassed with the Australian performance in the shock loss against Zimbabwe.

"The prognosis from me is I'm on a plane in the next 24 hours to go home and have scans and see what the results are and go from there.

"It's disappointing ... but I'm confident we can still win this series. But we've obviously got to play a lot better than that."

On a day of drama involving the skipper, Clarke could barely straighten his left leg as he hobbled between the wickets before retiring hurt.

Clarke defied medical opinion to return and stand at the non-striker's end for the final two balls of Australia's 9-209 total.

Then with Australia floundering in the field, Clarke decided he couldn't cop it anymore after 18 overs and came onto the field to try and lift the intensity of his teammates.

Although it was to no avail, Clarke shocked again when he even took the ball to bowl in the 47th over in a final act of desperation for the cause.

He doesn't know if he's done more damage to his hamstring by doing so.

"If things weren't going to go the way I wanted ... I wanted to make sure I was accountable for that," he said.

The skipper did admit in a pre-match press conference that he could feel the hamstring when batting - but that it wasn't restrictive.

Regardless of whether playing was a mistake or not, Clarke's courage under duress - just a few months after his Cape Town heroics - couldn't be questioned.