I didn't even want to go there, as I've studied this for decades and it's still beyond me!!!
Had pondered if Eriksen, before a big game, had a traditional nordic dish he loves (nurtured playing in cold weather, where sodium rich foods dominate to keep cellular hydration/osmotic pressure focused on maintaining heat - as nature provides us foods richer in Sodium in Winter, Potassium Summer (or hot cold conditions if more extreme weather based). So, he is way higher in sodium the morning of the game, bit dehydrated and thinks it's just nerves... He's doesn't get enough potassium to balance his cellular pressure to cool, so he fries on the pitch...
It more than crossed my mind... but it's just a thought.
I don’t think a cold windy summer night in Copenhagen is to blame, especially considering the player is resided in Italy