Sydney : Azhar Ali and Younis Khan kept Pakistan afloat after rookie Peter Handscomb made it three centurions in Australia's big first innings declaration at the third Sydney Test on Wednesday.

The tourists, who have already lost the series after defeats in Brisbane and Melbourne, made a rocky start after Steve Smith called a halt at 538 for eight, leaving seven overs for Pakistan to negotiate before tea.

They lost debutant Sharjeel Khan and Babar Azam in one Josh Hazlewood over before the interval with just six runs on the board.   

But the in-form Azhar and 114-Test veteran Younis steadied the ship with a century stand to take the tourists to stumps at 126 for two.

Azhar, who scored an unbeaten 205 in last week's Melbourne Test, was on 58 with 39-year-old Younis providing support on 64 to trail Australia by 412 runs.

"At two for six we were in serious strife, but to see the resilience, character and intent that has been shown by Younis and Azhar has been a real example to the rest of the dressing room of how we need to play," coach Mickey Arthur said.

Azhar had an escape nearing stumps on 51 when David Warner could not hold a sharp one-handed catch at leg-slip off Nathan Lyon.

Azhar was eight runs short of Mohsin Khan's 1984 record for the most runs (390) for Pakistan in a series in Australia, having tallied 382 at the close, while Younis reached 1,000 Test runs against Australia.

Handscomb completed his second century in just four Tests to join David Warner (113) and Matthew Renshaw (184) in another huge Australia innings against the beleaguered tourists.