The UEFA Champions League comprises three qualifying rounds, a play-off round, a group stage and four knockout rounds.
In matches in the three qualifying rounds and the play-off stage, clubs play two matches against each other on a home-and-away basis. The club which scores the greater aggregate of goals qualifies for the next round, with away goals and then penalties used to determine the winner in the event of a draw.
The ten winners in the play-off round ties – five from the best-placed path and five from the champions path – join 22 automatic entrants in the 32-team group stage. The clubs are split into eight groups of four teams, who play home and away against each of their pool opponents between September and December to decide which two teams from each section advance to the first knockout round. The third-place finishers in each group enter the UEFA Europa League round of 32.
From the last 16 until the semi-finals, clubs play two matches against each other on a home-and-away basis with the same rules as the qualifying and play-off rounds applied. In the last 16, group winners play runners-up other than teams from their own pool or nation, while from the quarter-finals on the draw is free.
The final is decided by a single match, which this season will be played at Fußball Arena München on Saturday 19 May 2012.
Further details, including the criteria for separating teams that finish level on points in a group, can be found in the official competition regulations.
Never before has a stadium been awarded Europe's premier club fixture twice in three years but hosting the 2013 UEFA Champions League final is Wembley's reward for the spectacular success of the 2011 event. It also marks the 150th anniversary of the Football Association (FA)'s foundation.
The decision was taken by the UEFA Executive Committee in Nyon on 16 June 2011 and means the fixture returns to Wembley for a record seventh time, the second since the stadium was rebuilt. "Given the exceptional nature of this historic moment in our beautiful game, and the fact that we will also celebrate 150 years of the Laws of the Game, we felt it was our duty at UEFA to help the FA celebrate in some special way," UEFA President Michel Platini explained.
London will also stage the 2013 UEFA Women's Champions League final and Champions Festival, which in 2011 were at Fulham FC's Craven Cottage and Hyde Park.
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