Michael Clarke has identified Mitchell Johnson's rediscovered hunger to play Test cricket as the catalyst for the batting and bowling double that has dominated the second Test.
Johnson is within reach of his second Test century to complement a brutal bowling display that shredded Sri Lanka and inspired a day of inevitable fortunes at the MCG.
Clarke scored an inevitable century, his fifth of the year, to become Australia's leading scorer in a calendar year.
Equally inevitably, Shane Watson missed out on a hundred. He holed out 17 runs short, his disappointment compounded when it was announced last night that he was injured again and in doubt for next week's third Test.
Watson injured his left calf bowling on day one and may not bowl again in the current Test.
Physiotherapist Alex Kountouris admitted the Australian vice-captain was far from certain to play in Sydney.
"He was able to get through the batting innings today and is likely to field on day three (today)," Kountouris said.
"Whether he bowls in the second innings will be determined closer to the bowling innings.
"A decision on his availability for the New Year Test will be made after the completion of the current match."
And it was predictable that Johnson would again pair his strong bowling performance with a buoyant batting effort that will leave him eyeing off a second Test ton today.
Johnson is 73 not out in Australia's tally of 8-440, a 284-run lead.
"Mitch is back to his best," Clarke said. "He has got the hunger back after his time away from the team.
"You don't devalue how much it means to play for Australia but everyone gets to a stage in their career when they don't have that hunger you need to be successful at the highest level.
"He has got that back."
Batting to create a commanding position so early in the Test, Australia used the day to stockpile runs against Sri Lanka's spirited but depleted attack.
Australia were in control after scoring 290 in the day and given the steep bounce in the MCG pitch, one of the best produced in more than a decade of drop-in surfaces, their pace attack should relish today's onslaught at Sri Lanka's talented but brittle line-up.
As Clarke became Australia's most prolific run-scorer in a calendar year his team sought to ensure the year finishes as it started. Clarke's tally for the year now stands at 1595 runs after he passed Ricky Ponting's previous record of 1544.
The captain's 106 was the mainstay of an MCG record stand of 194 with Watson that swept the Test away from Sri Lanka.
Watson has two career tons but he is better known for his failures to reach the milestone.
He has been dismissed eight times between 78 and 97 and fell for 83 when he toed a pull to a fieldsman in the deep.
He has got the hunger back after his time away from the team."Michael Clarke