Irfan made the most of his towering height on a bouncy pitch at the Gabba to help bowl Zimbabwe out for 215 in 49.3 overs, despite a late rally from captain Elton Chigumbura (35no) after Pakistan had posted a modest 235-7.
Pakistan, beaten by India and West Indies in their previous matches, slumped to 4-2 after choosing to bat as Tendai Chatara (3-35) removed openers Nasir Jamshed and Ahmed Shehzad cheaply.
The task of rebuilding fell to skipper Misbah-ul-Haq, who batted for almost 43 overs to top-score with 73 off 121 balls – an innings that featured just three boundaries.
Haris Sohail (27) and Umar Akmal (33) shared stands of 54 and 69 respectively with their captain but it took some hefty lower-order hitting to propel Pakistan past 200 after Shahid Afridi was bowled by Sean Williams for a second-ball duck.
Sohaib Maqsood helped himself to 21 off 17 balls but it was Wahab Riaz who played the standout innings, striking six fours and the only six of the innings to race to an unbeaten 54 off only 46 balls.
Zimbabwe’s openers also struggled to make their mark as Irfan proved a handful, forcing Chamu Chibhabha (nine) and Sikandar Raza (eight) to edge to Sohail at slip.
Irfan grabbed the next wicket to fall too, but not before Hamilton Masakadza (29) and Brendan Taylor (50) had added 52 for the third wicket.
Wicketkeeper Taylor bolstered Zimbabwe’s position in partnership with Williams (33), adding a further 54 runs, and reached his half-century off 69 balls.
At 128-3 in the 30th over, Zimbabwe’s chase was firmly on track only Riaz (4-38) to claim a major breakthrough when Taylor was out strangled down the leg-side.
Pakistan claimed a second crucial blow when left-arm seamer Rahat Ali, playing ahead of Younis Khan, induced a false shot from Williams who hung his head after cutting the ball straight to Ahmed Shehzad.
From that point wickets fell at regular intervals, Irfan having Solomon Mire caught behind before Riaz removed Craig Ervine and Tawanda Mupariwa in the space of three balls to make it 168-8.
Chigumbura kept Zimbabwe???s hopes alive with some lusty hitting and after 46 overs his side were 202-8 in comparison to Pakistan???s 202-6 at the same stage of their innings.
Afridi – yet to take a wicket in the tournament – slipped through a maiden to leave Zimbabwe needing 34 off 18 balls, a task that proved beyond their reach.