A Europa League clash between Sturm Graz and AEK Larnaca descended into chaos after one of the linesman was struck with an object from the crowd.
Swedish assistant referee Fredrik Klyver hit the turf in agony and was left needing stitches at Austrias Liebenauer Stadium and the game, which ended 2-0 to Larnaca, had to be stopped for 30 minutes.
Klyver was visibly shaken, eventually making his way off the field with a bandage around his head, and had to be replaced by the fourth official before the match could continue.
The fan who through the cup made a quick exit but was later caught and Sturm Graz apologised for the deplorable actions of the supporter in question.
This behaviour of a fan in todays Uefa Europa League game is by no means acceptable, an official statement from the club read.
This damages the reputation of football and us as a club.
We always try to see football as a positive celebration and to tackle these things. Fair play is our top priority. We are sorry that today we have disappointed many football fans.
The cup thrower was caught. The possible punishments will be considered.
Sturm Graz wishes the linesman all the best and speedy recovery.
Stefan Johannesson, head of the Swedish FA, believes the match should have been abandoned after the injury to Klyver.
He told Aftonbladet: It is Uefa who decides, but personally, I do not understand why they make such a decision.
Had this happened in Sweden, we would have [abandoned] the match.