Ireland captain William Porterfield won the toss and elected to bat in the must-win World Cup Pool B match against Pakistan at the Adelaide Oval on Sunday.
The winner will advance to the quarter-finals, while the loser needs a superior run-rate over the West Indies, whose last match against the United Arab Emirates began in Napier earlier on Sunday.
Pakistan made two changes from the side that upset South Africa, bringing in right-arm seamer Ehsan Adil and all-rounder Haris Sohail in place of the injured Mohammad Irfan and senior pro Younis Khan.
The seven-foot tall Irfan was ruled out with a hip injury, but a bigger surprise was dropping the experienced Younis for the key game.
Ireland: William Porterfield (capt), Paul Stirling, Ed Joyce, Niall O’Brien, Andrew Balbirnie, Gary Wilson (wkt), Kevin O’Brien, John Mooney, Alex Cusack, George Dockrell, Stuart Thompson.
Pakistan: Misbah-ul-Haq (captain), Ahmed Shehzad, Sarfraz Ahmed (wkt), Haris Sohail, Umar Akmal, Sohaib Maqsood, Shahid Afridi, Wahab Riaz, Rahat Ali, Sohail Khan, Ehsan Adil.
Umpires: Marais Erasmus (RSA), Ruchira Palliyaguruge (SRI)
TV umpire: Simon Fry (AUS)
Match referee: Ranjan Madugalle (SRI))