UEFA has revealed details of new Covid-19 protocols ahead of the Nations League kicking off this week.
European football's governing body has approved new principles for upcoming international matches, in case of games being postponed or cancelled due to coronavirus.
Northern Ireland kick-off their Nations League campaign on Friday against Romania in Bucharest.
They then welcome Norway to Windsor Park next Monday, September 7.
The Republic of Ireland travel to Bulgaria on Thursday before a home clash against Finland on Sunday.
Most UEFA member associations have obtained exemptions from their national/local authorities allowing teams to travel to match venues and their players to return to their clubs after international duty.
However, UEFA says that any positive Covid-19 cases from tests conducted before the matches may result in "groups of players or entire teams being placed into quarantine and national associations being unable to field a team for a specific match, following a decision of the relevant competent national/local authority".
They also said that due to a congested fixture schedule, it might be impossible to reschedule some of the 2020/21 UEFA Nations League.
Based on this situation, the UEFA Executive Committee has approved four principles.
A match will go ahead if a team has a minimum of 13 players (including at least one goalkeeper) available to play and have tested negative.
However, the local health authorities will always have the power to prevent a game going ahead.
If a team has fewer than 13 players available then UEFA will attempt to reschedule the game which could be in a neutral country.
If the game cannot be rescheduled, the national association responsible for the match not taking place will be declared to have forfeited the tie.
If both/neither are responsible, then the outcome of the game will be decided by drawing of lots, (i.e. win 1-0, loss 0-1 or draw 0-0) carried out by the UEFA administration.
The fourth principle is if any member of the referee team tests positive, then UEFA may appoint replacement match officials who may be of the same nationality and/or may not be on the FIFA list.
