• Smith scores 17th century
• Australia hold 22-run first innings lead
• Rain brings early end to play

Smith remained resolute, however, and as dark clouds drifted ominously over the stadium, he cut Sohail for three runs past point to bring up his century from 168 balls.

Usman Khawaja earlier missed out on a sixth ton, adding only two runs to his overnight 95 before he was caught behind playing a loose drive off paceman Wahab Riaz.

Khawaja's wicket was a reward for some rare sustained pressure by Pakistan's pacemen but they promptly loosened their grip, allowing Smith and Peter Handscomb to race to a 92-run partnership on a hot and humid morning.

Handscomb marched to his half-century, his third score over 50 in his first three tests, but was out for 54 when he sliced Sohail straight to Sami Aslam at point.