* Clarke scores fifth ton for the year
* Sri Lanka hit back with three wickets
By Ian Ransom
MELBOURNE, Dec 27 (Reuters) - Michael Clarke struck a sparkling century to help drive Australia to a first innings lead of 176 runs at tea on day two of the second test on Thursday, but Sri Lanka hit back with three wickets to hold hopes of saving the match.
The Australian skipper combined with all-rounder Shane Watson for a record-breaking fourth-wicket partnership of 194 against Sri Lanka at the Melbourne Cricket Ground, and registered his fifth century for the year before being caught in the slips for 106.
Clarke had earlier become his country's most prolific run-scorer in tests in a calendar year when he surpassed Ricky Ponting's 1,544 runs in 2005, and now sits fourth on the all-time list, with the chance of one more inning to play in 2012.
Clarke's dismissal sparked a middle-order collapse, however, as Watson followed his captain back to the dressing room for 83 in the following over and wicketkeeper-batsman Matthew Wade for a solitary run, both off the bowling of seamer Dhammika Prasad.
Mike Hussey also had a life on seven when he was dropped by replacement wicketkeeper Kumar Sangakkara and went to tea on that score.
Paceman Mitchell Johnson was on 11 not out, as Australia moved to 332-6.
Sri Lanka will hope for quick wickets after the break to mitigate the damage but face a task to uproot the in-form Hussey who averages over 100 against them.
Clarke and Watson resumed after lunch with the score 238-3 on another day of brilliant sunshine and set about punishing Sri Lanka, who were skittled for 156 on the first day.
Both were dropped late on day one and Clarke survived another life three overs before lunch when on 58, when Sri Lanka captain Mahela Jayawardene spilled a sharp chance in the slips from spinner Rangana Herath.
Clarke brought up his ton with an aggressive hook shot that rocketed fine to the boundary but was out soon after when he was caught by Jayawardene in the slips off Shaminda Eranga.
That broke Clarke's astonishing record of going on to score at least a double-century after surpassing 100 in 2012, which he had achieved four previous times this year.
Watson's half-century was his first in eight innings, and a welcome return to form after struggling to capitalise on a number of starts, but he rued a rash hook shot off Prasad that went straight to Thilan Samaraweera in the deep.
The 83 was Watson's 19th half-century, but the barrel-chested all-rounder has only a paltry two test centuries to his name.
Wade was out for one off Prasad, attempting another ill-chosen hook that sailed down the throat of Eranga near the rope.
Sri Lanka's fightback was achieved without seamer Chanaka Welegedara who went off the ground with an apparent hamstring injury in the morning session.
The tourists were already a man down, with wicketkeeper Prasanna Jayawardene suffering a broken thumb on day one.
(Editing by Greg Stutchbury)