Clarke was forced to retire hurt while batting on the fourth day of the opening match of the series in Hobart and while Australia are reluctant to risk aggravating the injury further, the 31-year-old has shown improvement over the last few days.
The leading test run scorer this year put himself through batting and fielding practice on Tuesday and sounded confident he would be fit to start the match.
"I'm still pretty positive I'll be right for tomorrow," he told a media conference. "I haven't run at 100 percent but I've certainly built up over the last three days."
Clarke said he was "improving every day" but would have to wait until the morning of the match to see if there was any reaction to Tuesday's practice.
"I did a fair bit of running today in the indoor nets. A decision can't be made today," he added. "I really need to wait and see how I pull up tomorrow morning."
Waiting in the wings should Clarke not make the test is top-order batsman Usman Khawaja, though coach Mickey Arthur was leaning towards the skipper taking the field in front of a huge crowd at the MCG.
"If I was a betting man I'd bet on Michael Clarke leading the team out on Boxing Day," he said.
"We've got to be mindful as well, much like the Mitchell Starc decision, as to the amount of important cricket we've got coming up."
Australia have opted to rest 22-year-old paceman Starc as part of a controversial rotation policy after a swathe of injuries decimated their pace bowling stocks.
Front-line seamer Ben Hilfenhaus has been ruled out with a side strain, joining James Pattinson and Pat Cummins on the sidelines.
Mitchell Johnson, who was dropped following the third test against South Africa, has been recalled to the side while Jackson Bird, the leading wicket-taker in the domestic Sheffield Shield, has been called up for his first test.
Only Peter Siddle, who took nine wickets in a man-of-the-match performance at Hobart, has been retained in the pace attack while off-spinner Nathan Lyon has also kept his place.
Australia lead the three-match series 1-0, with the third test scheduled to begin in Sydney on Jan. 3.
