All matches in the preliminary round are played in the form of mini-tournaments hosted by one of the participating associations.
Each team plays each of the other teams in the group once, with three points awarded for a win, one for a draw and none for a defeat.
When establishing the match schedule, the host association is placed in position 1, and the visiting teams in positions 2, 3 and 4, according to their coefficient rankings.
The teams in the preliminary round are drawn into three, four or five groups of four, depending on the number of entries. All group winners and, if required, the best runners-up qualify for the main round.