Video Assistant Referees will be used at this summer's Nations League finals, UEFA has announced.
After a successful introduction into UEFA's club competitions in the Champions League knockout stages and Europa League final, the system will be used during this week's competition involving England, Holland, Switzerland and hosts Portugal.
A VAR team will be based at each stadium to support the referee and check for "clear and obvious" errors relating to goals, red cards, penalty-box incidents or mistaken identity.
The head coaches of the four participating nations were briefed in April by UEFA's chief refereeing officer Roberto Rosetti to prepare for the use of VAR at the finals.
England coach Gareth Southgate said: "We had positive experiences of VAR in the World Cup.
"My feeling both internationally and domestically is that, in the main, the big decisions have been right. The purpose of using VAR is to help the referees so I think it has been a help.
"You will never get a system that is 100 per cent fail-safe but the key decisions that are clear and obvious have been rectified. For me, that is a positive."
Portugal's Fernando Santos hailed the system as "a step forward for all people who love football and fair play", but Holland boss Ronald Koeman said: "I am in favour of the VAR tackling the big, obvious issues only, rather than to search endlessly for potential errors."
Switzerland's Vladimir Petkovic stressed: "It is important that in the end it is still man who decides, not a machine."