Captain Michael Clarke's remarkable stretch of form this year continued on Thursday, when a superb century carried Australia to 440 for eight on day two of the second Test against Sri Lanka at the Melbourne Cricket Ground.

Resuming on 150 for three in response to the opposition's mere 156 all out, the hosts rode to a hefty 284-run lead on the back of Clarke's dominance, all-rounder Shane Watson's aggression and lower-order striker Mitchell Johnson's enterprise.

Sri Lanka, meanwhile, lamented the depleted nature of their XI - after seamer Chanaka Welegedara was sidelined by a hamstring injury and wicketkeeper-batsman Prasanna Jayawardene remained off the field with a fractured right thumb.

Welegedara's absence increased spinner Rangana Herath's workload, while the veteran Kumar Sangakkara was rather ineffective as Jayawardene's replacement behind the stumps, dropping a relatively simple catch and missing a reasonably straightforward stumping opportunity.

Clarke, for his fifth century of the year and 22nd of his career, was characteristically outstanding. Leading from the front in every sense of the term, the talented right-hander became the country's highest run-scorer in a calendar year, surpassing the impressive tally of 1,544 amassed by former team-mate Ricky Ponting.

Watson again proved at home at four in the order en route to 83 during a solid 194-run alliance alongside his skipper, but will rue the shot that robbed him of three figures, while the left-handed Michael Hussey was undone by a brilliant catch in the deep by Herath. Running backward, on the dive and with one hand, the Sri Lankan fielder sent Hussey packing for 34.

Wade's failure demanded success from at least one of would be all-rounders Mitchell Johnson and Peter Siddle. The former promptly delivered, digging in to the tune of an unbeaten 73. Well supported by Siddle across their 58-run alliance, the hard-hitting Johnson will expect similar help from tail-enders Nathan Lyon and Jackson Bird come Friday, with a lead of 350-plus ripe for the picking.

Visiting seamers Shaminda Eranga and Dhammika Prasad, however, despite Welegedara's exit, will be eager to build on their respective hauls of two and three wickets. The pitch, indeed, isn't the flattest.