The 31-year-old injured his right hamstring in the first Test in Hobart last week and has been racing the clock to be fit to lead his side into a potential series-clinching victory.
He came through a variety of running drills under the watchful eye of physio Alex Kountouris in the team's final training session on Christmas Day, and remained optimistic of taking to the field in Melbourne.
"It's going okay, thank you. It's improving every day," Clarke said of his hamstring. "I did a fair bit of running today in the indoor nets.
"I can't make a decision now. I need to wait and see how I pull up tomorrow morning, from the workload yesterday and then again at training today.
"Like I've said from day one, I'm still pretty positive that I'll be right for tomorrow."
Should Clarke fail to take his place in the side, Usman Khawaja will come in and Shane Watson will captain Australia.
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