Josh Inglis suffered defeat in his first game as new Australia captain as Pakistan's teenage debutant Arafat Minhas bagged a stunning five-wicket haul and then smashed the winning runs with a six to secure a comprehensive victory in Rawalpindi.
Inglis, handed the task to lead the side with Mitch Marsh ruled out with an ankle injury, saw his side struggle to handle Minhas' tricky left-arm variation as the 19-year-old plundered 5-32 to put the visitors on the backfoot.
Australia' own teen debutant, Ollie Peake, who became the tourists' youngest ever specialist ODI batter at 19, could only make seven as his side struggled to post 200 in the opening match of the three-game series.
And Pakistan always looked comfortable overhauling their target thanks to a solid century partnership between Babar Azam and Ghazi Ghori with Minhas capping a brilliant performance by striking a towering six to seal the five-wicket victory with 45 balls remaining.
