Clarke spent about an hour training at the MCG on Tuesday morning as he sought to prove he had recovered from a hamstring strain he suffered in last week's Test against Sri Lanka in Hobart. Tuesday's session included running drills, about 25 minutes batting in the nets, a short stint running between wickets and also some slips catching. All were done under the supervision of team physiotherapist Alex Kountouris.

After the session, Clarke said he was optimistic of captaining Australia on Boxing Day for the second time but was unable to guarantee he would.

"It's going OK. It's improving every day," Clarke said when asked about the condition of his right hamstring.

"I can't make a decision now . . . I need to wait and see how I pull up tomorrow morning, from the workload yesterday and the training today.

"Like I've said from day one, I'm still pretty positive I'll be right for tomorrow.”

Clarke said he was confident he would not let his heart rule his head in deciding whether to take his place in the team ahead of standby batsman Usman Khawaja.

"Having experts around me. Alex (Kountouris) has been around international cricket for such a long time. He's seen me do my hamstrings on plenty of occasions, he's seen plenty of guys go through it," he said.

"We'll try and make the best decision for the team, there's no doubt about that. I certainly won't go into the game tomorrow if I feel it's going to affect my batting. If I feel I can't perform at my best I certainly won't take any part, but if I can I'm really keen to get out there and be a part of it."

Clarke said if he was unable to play he had no reservations about vice-captain Shane Watson's ability to lead the team against Sri Lanka.

smh.com.au