Labuschagne, coming off his career Test-high 215 in the first innings, was given a 'life' on four when Todd Astle dropped a regulation caught and bowled chance at abdomen height.
He typically settled into his innings and played a number of reverse sweeps to keep the scoreboard ticking over.
Joe Burns again failed to go on after a start and lost a leg before wicket review after not picking leg-spinner Todd Astle's wrong'un. Burns, who has failed to nail down the opener's spot alongside Warner, was out for 40 off 79 balls with two sixes. Burns finished the Test summer with 256 runs at 32.00.
Australia have been unbeatable this season, winning all four Tests at home -- two each against Pakistan and New Zealand -- after retaining the Ashes by drawing the series 2-2 in England.
The Test is being played against the backdrop of one of Australia's most devastating bushfire seasons with at least 24 people losing their lives in blazes raging across the country, including on the outskirts of Sydney.
Play will be suspended in the match at the umpire's discretion, should smoke significantly affect air quality or visibility, but the sky above the ground has remained largely clear so far.