The bespectacled 26-year-old, who was not out on 132 at the close, added 105 runs with fellow opener Abdullah Shafique to give Pakistan a strong start after captain Babar Azam‘s decision to bat.
Pakistan on 🔝 at stumps on Day 1 💪Imam-ul-Haq (132*) and Azhar Ali (64*) have put the hosts in a dominant positio… https://t.co/dg2Lt8NMJX
— ICC (@ICC) 1646398388000
His 140-run stand for the unbroken second wicket with Azhar Ali, who was 64 not out, further consolidated Pakistan’s position on a flat pitch where Australia rued not playing a second spinner.
Imam’s 271-ball knock included 15 boundaries and two sixes.
Australia are in Pakistan for the first time in 24 years for a full tour, which could potentially lead to regular visits by top teams who have largely stayed away since a 2009 attack on the Sri Lanka team bus in Lahore.
However, at least 30 people were killed on Friday in a suicide bombing at a Shi’ite mosque in Peshawar, some 140 kilometres (87 miles) away from Islamabad where the Australian team are staying.
Australia players wore black armbands in memory of former wicketkeeper Rod Marsh who died aged 74 on Friday. The teams also observed a minute’s silence for the Australian stalwart.
Earlier, Josh Hazlewood returned from a side injury to replace Scott Boland in Australia’s three-pronged pace attack but an early breakthrough eluded the tourists.
Australia captain Pat Cummins used up a review trying to get Imam lbw by Mitchell Starc, then introduced spin in the eighth over.
Abdullah stepped out to hit Lyon over the long-on rope for a six and Imam would later give Australia’s frontline spinner the same treatment.
Lyon finally broke the stand when Abdullah stepped out only to sky the ball high in the air, allowing Cummins to run from mid-off to take a tumbling catch.
All-rounder Cameron Green, who was not even born when Australia last toured Pakistan in 1998, was pressed into attack after lunch but Imam and Azhar ended up batting through the last two sessions to frustrate Australia.
Imam threaded a Starc delivery through the off-side for a four to bring up his hundred after tea.
Cummins used eight bowlers, including part-time spinners Travis Head, Marnus Labuschagne and Steve Smith, but it was a day of toil with little success for the tourists.