Wednesday's Dutch Cup semi-final between Feyenoord and Ajax was halted for 30 minutes after Davy Klaassen was struck on the head by an object thrown from the stands.
Ajax midfielder Klaassen was celebrating near the corner flag at De Kuip early in the second half when what appeared to be a lighter caught him on the back of the head.
The Netherlands international was left bleeding and referee Allard Lindhout took the decision to take both sets of players off the field.
After a stoppage of half an hour, during which time Feyenoord assistant John de Wolf urged home fans to "use their common sense", play eventually resumed.
Klaassen attempted to continue but he went down holding his head soon after and was replaced by Brian Brobbey.
But the 30-year-old ultimately had the last laugh as his goal proved to be the winner as Ajax held on to win 2-1 and advance to the final, where PSV await on April 30.
Your King of the Match! pic.twitter.com/LD2WhLOhOJ
— AFC Ajax (@AFCAjax) April 5, 2023
"These are always crazy matches when you play here," Klaassen later told ESPN. "But we didn't expect this. It goes beyond all limits.
"I felt something pretty hard. At first I felt anger inside, and I got even angrier when their goalkeeper [Timon Wellenreuther] ran over and shouted that I had to get up.
"Then another player looked at my head and it turned out I was covered in blood. I wanted to get away from the sidelines.
"I then had a throbbing feeling in my head and had trouble focusing so had to come off."
Klaassen added that he is not sure yet whether he intends to press charges, with local police reporting that a 32-year-man had been arrested in connection with the incident.
Away fans have not attended 'De Klassieker' games since 2009 in an attempt to quell violence in the stands.