The UEFA Champions League (UCL), usually known simply as the Champions League, is an annual club association football competition organised by the Union of European Football Associations (UEFA) that is contested by top-division European clubs. The competition begins with a round robin league phase to qualify for the double-legged knockout rounds, and a single-leg final. It is the most-watched club competition in the world and the third most-watched football competition overall, behind only the FIFA World Cup and the UEFA European Championship.