Australia captain Aaron Finch said Thursday he could pull out of his team's pivotal final Super 12 match at the Twenty20 World Cup against Afghanistan because of a hamstring injury.

Finch hit form on Monday with a 44-ball 63 in the win against Ireland but was unable to field after feeling a "twinge" during Ireland's innings.

The defending champions will probably have to beat Afghanistan on Friday by a big margin in Adelaide to have any chance of making the semi-finals as one of the two top teams in Group 1.

But opener Finch and middle-order batsman Tim David, who also has a hamstring niggle, are struggling to be fit.

"I will test out properly this afternoon to make sure that I am not hindering the side at all leading into the game," said Finch.

"Because that's the worst possible scenario that you leave the guys short out there with one player fewer."

David hurt his hamstring while batting and did not take field in Ireland's chase.

"He is in exactly the same boat. We will know more during training," said Finch.

Wicketkeeper Matthew Wade will lead Australia if Finch has to sit out.

Australia began their campaign with a big loss to New Zealand which left them with a poor net run rate which could now jeopardise their semi-finals chances.

Third in Group 1, but level on five points with New Zealand and England, Australia's fate will depend on other results even if they beat Afghanistan handsomely.

"I think the reality is our first game has put us in this situation, so that's OK," said Finch.

"We knew for the rest of the tournament it's going to come down to run rate if things go well.

"But there are still two (other) games to be played in the pool as well, so first and foremost we've got to get those two points."

New Zealand play Sri Lanka in the first match of an Adelaide double-header on Friday, while England face Sri Lanka on Saturday in Sydney in the final Group 1 encounter.

Afghanistan, who are out of the final-four race after two of their matches were washed out, have injury concerns over leading spinner Rashid Khan.

Rashid struggled with his back and a knee problem in the defeat to Sri Lanka, but assistant coach Rais Ahmadzai said Thursday he was "fine and training" and the side wanted to finish the tournament in style.

"It's really not an easy game for us, to play against Australia in Australian conditions, but we are here to give them a tough time," said Ahmadzai.

"I think Australia will be under pressure because they want to win, and we are here to finish the tournament with a high morale."