The tournament consists of several stages and begins with three preliminary knockout qualifying rounds. In each subsequent preliminary round, participating teams are paired, with aggregate winners proceeding into the next round. The sixteen winners of the final qualifying round are joined by the sixteen teams who have qualified directly, to participate in the group stage. They are drawn into eight groups of four teams, each team playing every other team in the group twice (home and away). The top two teams from every group qualify for the next round. Here the sixteen remaining teams take part in the knock-out stages. All qualifying round and knock-out ties are two-legged, with each team hosting one match. The team which scores the greater aggregate number of goals qualifies for the next round. The final, which is a single match played at a predetermined venue.