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.
Home to FC Bayern München and TSV 1860 München, the Fußball Arena München will host the 2012 UEFA Champions League final following a decision made by the UEFA Executive Committee in January 2009. The showpiece will take place on Saturday 19 May 2012.
• The Fußball Arena München took less than three years to build from start to finish, and was completed on 30 April 2005. It was conceived following a referendum in October 2001 when 65.8% of Munich's citizens voted to construct a new arena rather than regenerate the Olympiastadion, venue for the 1972 summer Olympic Games and previous home of Bayern and 1860 München.
• A year to the day after that vote, work commenced on the stadium, including the construction of the unique exterior. The Fußball Arena München's transparent outer wall is comprised of foil panels which are lit from the inside and can change colour depending on who is playing; red for Bayern, blue for 1860 München and white for Germany.
• The arena opened its doors to competitive football on 5 August 2005 when a full house of 66,000 watched Bayern defeat VfL Borussia Mönchengladbach 3-0. In January 2006, city authorities approved a 3,901 increase in capacity which means the stadium can now house 69,901 supporters. Some of these reside in standing terraces which are created for domestic games by converting 10,400 seats in each of the north and south stands.
• Located on Werner-Heisenberg-Allee – named after famous German atomic physicist and 1932 Nobel Prize for Physics winner Werner Heisenberg – the Fußball Arena München played host to the opening game of the 2006 FIFA World Cup, Germany's 4-2 victory against Costa Rica. A further five matches in the tournament were played at the arena, including France's 1-0 semi-final win against Portugal.
• While some 106 VIP boxes, 400 media seats and 11,000 parking spaces cater for those attending the game, the players make do with two warm-up rooms, a nursery and four changing rooms – one each for Bayern, 1860 München and their respective opponents.
• The Olympiastadion hosted three European Champion Clubs' Cup finals. Trevor Francis's strike earned Nottingham Forest FC victory against Malmö FF in 1979 and there was also only one goal in it 24 years later when Olympique de Marseille beat AC Milan to claim the inaugural UEFA Champions League title. In 1997 two Karl-Heinz Riedle efforts set BV Borussia Dortmund on course for a 3-1 win against Juventus.
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