Azhar Ali dug in for an unbeaten 66 as Pakistan reached 142 for four against Australia on a rain-affected first day of the Boxing Day Test.

Pakistan batted cautiously during the 50.5 overs that were possible at the MCG but still lost wickets at regular intervals, Jackson Bird taking two for 53.

Sami Aslam was undone by Nathan Lyon after making just nine and after Azhar and Babar Azam batted through the remainder of Monday morning, Azam edged the last ball before lunch from Josh Hazlewood to give Steve Smith his second catch.