Boyd Rankin, who had previously taken one wicket in a lone Test appearance for England before switching to Ireland, made the breakthrough.
With the last ball of the eighth over, Rankin had Azhar Ali out for four runs as he edged tentatively to Ireland captain William Porterfield at second slip.
And the very next ball 13 for one became 13 for two when left-hander Imam-ul-Haq, who was also making his Test debut, was lbw for seven to a Tim Murtagh delivery that came back into him.
The Test got off to a dramatic start when Imam was injured on the first ball.
Azhar Ali dug out a single off the opening delivery from Tim Murtagh and called for a quick legside single. Non-striker Imam, in scrambling to complete the run, found himself sandwiched between wicket-keeper Niall O’Brien and Tyrone Kane in a heavy collision.
The 22-year-old left-hander was left flat on the ground and needed several minutes´ treatment on the field.
But he recovered and faced his first ball, the second of the match, from Murtagh with Imam, who had had a cold press applied to the back of his neck, playing and missing before he saw out the remainder of the over at a sunny Malahide.
Imam is the nephew of Pakistan selection chief and former Test batsman Inzamam-ul-Haq and his inclusion in the squad provoked allegations of nepotism.
But Imam, who hit a hundred on his one-day international debut against Sri Lanka last year, made fifties against both Kent and Northamptonshire in Pakistan´s two warm-up matches.
Rain washed out the whole of Friday´s scheduled first day but a day later grey clouds had been replaced by sunny blue skies as Ireland, from the moment of the toss, officially became the 11th nation to play men’s Test cricket.
The coin fell in favour of Ireland captain William Porterfield and he elected to field in this one-off match, with the teams lining up for national anthems before play started at 4pm PST.
Pakistan: Imam-ul-Haq, Azhar Ali, Haris Sohail, Asad Shafiq, Babar Azam, Sarfraz Ahmed (captain, wicketkeeper), Shadab Khan, Faheem Ashraf, Mohammad Amir, Rahat Ali, Mohammad Abbas
Ireland: William Porterfield (captain), Paul Stirling, Ed Joyce, Niall O’Brien (wicketkeeper), Andy Balbirnie, Gary Wilson, Kevin O’Brien, Stuart Thompson, Tyrone Kane, Boyd Rankin, Tim Murtagh