Cardiff's Principality Stadium is expected to host the opening match of Euro 2028 if the joint bid from the home nations and Republic of Ireland is successful.
The Welsh team would also play its matches at the 74,500-capacity stadium if it qualifies, with the final staged at Wembley.
The bid could also have tournament spots reserved for any two of the host teams failing to qualify in the normal way.
The football associations of Wales, Northern Ireland, England, Scotland and the Republic of Ireland, have joined forces in a move to stage the tournament with games played at venues across all five countries.
While negotiations continue with European footballing governing body Uefa it is understood that the "direction of travel" that tournament places would be left open for any two teams that failed to qualify through the group qualification stage.
The home nations and the Republic of Ireland are up against Turkey to host the tournament. A bid by Russia was lodged, but was subsequently rejected following its invasion of Ukraine.
The likelihood is that across the five nations a number of teams will qualify as of right for the tournament. However, say in the unlikely scenario that all five failed to qualify, the fall back places would most likely be based on the two strongest performances across the respective qualification groups rather than on world rankings.
If the bid between the UK and Republic of Ireland is successful, many of venues will be in England, but will also include Windsor Park in Northern Ireland, the Principality Stadium in Wales, Hampden Park in Scotland and the Aviva Stadium and Croke Park in Dublin.
Whether Wales qualifies as of right, through any fall back position, or not at all, it is expected to host the tournament’s opening game at the Principality Stadium and Wales matches if the joint bid is successful. Wales haven't played at the country's biggest stadium since 2018, preferring instead to make Cardiff City Stadium their home. That stadium, however, would not be part of the joint bid.
Uefa is expected shortly to confirm whether the tournament will have 24 or 32 teams competing.
The Football Association of Wales declined to comment if a fall back position for two nations that failed to qualify automatically to play in the tournament formed part of the bid talks with Uefa.
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