|Referee: Gianluca Rocchi (ITA) – Stadium: Stamford Bridge, London (ENG)|
|Referee: Milorad Mažić (SRB) – Stadium: White Hart Lane, London (ENG)|
|Referee: William Collum (SCO) – Stadium: Şükrü Saracoğlu, Istanbul (TUR)|
|Referee: Antony Gautier (FRA) – Stadium: Estádio do Sport Lisboa e Benfica, Lisbon (POR)|
|Referee: Fırat Aydınus (TUR) – Stadium: Stadion Luzhniki, Moscow (RUS)|
|Aggregate: 4-4 Basel win 4-1 on penalties|
|Referee: Olegário Benquerença (POR) – Stadium: St. Jakob-Park, Basel (SUI)|
|Referee: Pavel Kralovec (CZE) – Stadium: Stadio Olimpico, Rome (ITA)|
|Referee: Ivan Bebek (CRO) – Stadium: St James' Park, Newcastle (ENG)|
Last updated: 08/05/2013 14:55 CET
The UEFA Europa League comprises three qualifying rounds, a play-off round, a group stage and five knockout rounds.
In matches in the three qualifying rounds and the play-offs, 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 play-off round winners join the ten losers from the UEFA Champions League play-offs and automatic entrants. The clubs are split into 12 groups of four teams, playing home and away against each of their pool opponents between September and December. Two sides from each section advance, proceeding into the round of 32 alongside eight third-placed teams from the UEFA Champions League group stage.
From the last 32 until the semi-finals, clubs play two games against each other on a home-and-away basis with the same rules as the qualifying and play-off rounds applied. In the last 32, group winners and the four third-placed sides from the UEFA Champions League with the best records are seeded, guaranteeing they will play the second leg at home. Teams from the same group or the same association cannot be drawn together. From the round of 16 onwards the draw is free.
The final is decided by a single match, which this season will be played at the Amsterdam ArenA on Wednesday 15 May.
Further details, including the criteria for separating teams that finish level on points in a group, can be found in the official competition regulations.