There is so many surprising results tonight, I'm not even sure which one can be called as biggest upset.
European competitions are different than domestic league matches and big names might drop badly vs what was supposed a weaker team in a less known league..
Balkani taking 2:0 win against Dinamo Zagreb. Klaksvik got first ever point in UEFA tournament in Faroe Islands history. Their opponent Lille was tough one, but IIRC this season Klaksvik is still unbeaten at home in their European campaign.
Dinamo Zagreb defeat was unexpected even though they played away. They destroyed Astana by 5 goals to 0 then just lost like that vs a team playing in Kosovan league!
What happened to Ludogorets that they lost to Nordsjaelland so big - 7:1?
I didn't followed the game but that was definitely a shocking result! Same goes for Beşiktaş, they were leading with 2 goals then simply lost control in the last ten minutes of the game. They received a red card before that.