The Referees Committee appoints a referee for each match. Only referees from the official FIFA list of referees are eligible. The rest of the referee team is, in principle, proposed by the association of the referee, in accordance with criteria established by the Referees Committee. The host association may be requested to appoint referees.
The Referees Committee decides on the criteria for the appointment of video assistant referees for each competition stage.
UEFA arranges for the referee team to arrive at the venue the day before the match. If a member of the referee team does not arrive at the venue by the evening before the match, the UEFA administration and the teams must be informed immediately. The Referees Committee takes the appropriate decisions, which are final.
If a referee, assistant referee or video assistant referee becomes unfit to officiate or is otherwise incapacitated before or during a match, she is replaced by another member of the referee team as follows, in accordance with the IFAB Laws of the Game :
The referee is replaced by the fourth official or the video assistant referee if one has been appointed and is available on-site, or by an assistant referee.
An assistant referee is replaced by the fourth official or by the reserve assistant referee if one has been appointed.
A video assistant referee is replaced by the assistant video assistant referee (if certified as video assistant referee), or by the referee if she is unfit to referee but able and certified to serve as video assistant referee.
If necessary, the match will take place without video assistant referees and/or without a fourth official.