Lee Hodson’s Northern Ireland were beaten 1-0 by Poland in their Euro 2016 opener.
The Poles dominated the early exchanges but Michael O’Neill’s men proved tough to break down in the first 45.
They were, though, beaten just six minutes after the re-start when Ajax striker Milik latched onto Jakub Blaszcykowski’s cross and found the net with a left-footed shot.
Arguably Northern Ireland’s best chance fell to captain Steven Davis but he failed to get a shot away after a well-worked free-kick, leaving the Green and White Army with work to do in their final two fixtures.
Next up for Hodson and Co is a tough clash with Ukraine in Decines on Thursday.