18.07 As a rule, a player may not play in a UEFA club competition (i.e. UEFA
Champions League and UEFA Europa League, but not UEFA Super Cup) for
more than one club in the course of the same season. Exceptionally,
however, a player who has been fielded in the first, second or third qualifying round of the UEFA Champions League or UEFA Europa League is entitled to play in the UEFA Champions League or UEFA Europa League for another club as from the group stage, provided that his former club did not qualify for the group phase of either the UEFA Champions League or the UEFA Europa League; moreover, as from the start of the round of 32 (round of 16 for UEFA Champions League), a player can be registered in accordance with paragraphs 18.17 to 18.20 below. For the avoidance of doubt, a substitute player who has not been fielded is entitled to play for another club competing in the UEFA Champions League or UEFA Europa League in the course of the same season, provided that he is registered with the UEFA administration in accordance with the present regulations.