| 4dA Northern Irish referee was hit by an object thrown from the crowd in a Europa League qualifying match in Romania.
Referee Arnold Hunter received treatment on the field and was then replaced by the fourth official for the closing stages of the clash between Universitatea Craiova and Budapest Honved.
Hunter was separating tussling players in the final minute of extra-time when he was struck by what appeared to be a smoke bomb, with the match halted for half an hour.
Craoiva went to win 3-1 on penalties, with the game having remained goalless after extra-time.
European chiefs UEFA will review reports from the officials before gauging whether to issue any punishment.
"We are awaiting reports from the match delegate and the referee before deciding whether to take any action," said a UEFA spokesman.
Honved issued a statement condemning the "scandalous scenes", and branding the resumption of the match "unacceptable", putting players and officials at risk.
