The crucial moment
The decisive moment in this game came just five minutes into the second half as Milik scored the only goal of the game.
After a frustrating first half, Poland got a break as Jakub Błaszczykowski was freed down the right hand side before puling it back to Milik, who took a touch to compose himself and duly swept the ball into the bottom right corner, left footed.
A frustrating first half for Poland
From the very first minute, it was clear to see Michael O'Neill's gameplan for this one as he set his Northern Ireland team up to defend in numbers and frustrate Poland, which they did well for most of the game. The Northern Irish formation was effectively a 3-6-1, with Kyle Lafferty a very isolated figure up front.
However, despite the numerous bodies defending, Poland did still create a couple of clear openings in the match. Milik was the main man throughout for Adam Nawalka's team and he blew a big chance on the half hour mark. It was good play from Bartosz Kapustka on the right, who pulled it back to Milik who shifted it to his left, only to fire high and wide of the left post with the goal somewhat at his mercy.
The other big chance of the half fell to young starlet Kapustka, who made the most of Kamil Grosicki's slight knock as he played an outstanding game in his absence. Just six minutes remained in the opening period when he controlled well on his chest before volleying left footed from the edge of the box, only to see Michael McGovern pull off a flying save high to his right.
Poor quality second half
The second half was a quieter affair compared to the first, as once Poland broke through early in the half they were happy to just keep the ball and look for a second if the chance opened itself up. The closest they came to a killer second was through substitute Grosicki, who drilled one just wide of the near post on the right after the ball broke kindly for him.
The likes of Milik, Kapustka and Błaszczykowski remained busy throughout the half and loosely threatened the goal with attempts from distance, but there wasn't really a killer edge in attack for Poland as main man Robert Lewandowski struggled to get involved.
No Northern Irish threat
You will struggle to find another negative performance in a major tournament as much as this one was from Northern Ireland. Once their commendable defence had been broken down early in the second half, they lost their meaning in the game, with nothing to hold onto anymore.
O'Neill did try and change their approach by bringing on the likes of Connor Washington and Stuart Dallas, but they still struggled for any creativity and effectively handed a day off to Wojciech Szczęsny in the Poland goal.
The closest Northern Ireland came to what you would call a clear chance was five minutes from time when they caught the Poland defence out with a training ground free kick move to give Steven Davis a clear sight of goal, but he slipped at the crucial moment and couldn't get in an attempt on goal.