CAPTAIN Michael Clarke has broken predecessor Ricky Ponting's record for most Test runs by an Australian in a calendar year as his team entrenched its commanding Boxing Day Test position against Sri Lanka.

Australia added 88 runs without loss in the first session of day two to go to lunch at the MCG 3-238, with Clarke on 56 and deputy Shane Watson on 60. Their fourth-wicket partnership stood at 121.

When Clarke reached 56 shortly before the break, with a single off Dhammika Prasad, it took him past Ponting's previous record from 2005 of 1544 runs at 67.13. As of the lunch break Clarke's 2012 record was 1545 runs at an average of 110.36.

Sri Lanka had the opportunity to remove both batsmen shortly before lunch but squandered both opportunities off the bowling of finger spinner Rangana Herath, which admittedly were tough. Stand-in wicketkeeper Kumar Sangakkara missed a leg-side stumping when Clarke was on 54 while captain Watson's hefty back-foot cut was fumbled by captain Mahela Jayawardene at first slip.

Australia began day two at 3-150, with Watson on 13 and Clarke on 20. While the leaders' session scoring rate of just under three runs per over was subdued they rarely looked troubled by the Sri Lankan attack. The visitors were down one paceman after left-armer Chanaka Welegedara suffered a suspected hamstring strain while bowling the 10th over of the day.

Australia's batsmen were so solid that Sri Lanka captain Mahela Jayawardene elected to protect runs by employing a fielder at deep point, which offered both batsman a huge gap between gully and cover to nudge singles and rotate the strike.

One of Clarke's rare uncertain moments – before the stumping opportunity – occurred in the 54th over when he was struck on the helmet by a menacing bouncer from Shaminda Eranga. It had no noticeable effect on his demeanour.

When the captain brought up his half-century in the 60th over it marked a 100-run partnership with Watson. When his deputy reached the same milestone two overs later it took their partnership past their previous 103. That partnership came in the second innings of the 2009-10 Boxing Day Test against Pakistan, when Watson scored his first Test century – which remains his only century achieved in Australia.

Vice-captain Watson's half-century was his first in his eight Test innings.