Usman Khawaja finally found form again to stroke a fine century Sunday and steer Australia into a massive lead over Sri Lanka as the tourists battle to stay in the second Test at Canberra.

At stumps, the visitors were 17 without loss, chasing a huge 516 to win with two days remaining after Tim Paine declared Australia's second innings at 196 for three. Dimuth Karunaratne and Lahiru Thirimanne were both unbeaten on eight, weathering some 30 minutes before bad light stopped play slightly early. Sri Lanka had resumed the third day at 123 for three and in a hostile morning session lost four wickets and Kusal Perera, who retired after being hit on the head by a bouncer.