The tournament proper begins with a group stage of 32 teams, bests last years classified teams in each country league. Divided into eight groups. Seeding is used whilst making the draw for this stage, whilst teams from the same country may not be drawn into groups together. Each team meets the others in its group home and away in a round-robin format. The winning team and the runners-up from each group then progress to the next round. The third-placed team enters the UEFA Europa League.
For this stage, the winning team from one group plays against the runners-up from another group, and teams from the same association may not be drawn against each other. From the quarter-finals onwards, the draw is entirely random, without association protection. The tournament uses the away goals rule: if the aggregate score of the two games is tied, then the team who scored more goals at their opponent's stadium advances.
The group stage is played from September to December, whilst the knock-out stage starts in February. The knock-out ties are played in a two-legged format, with the exception of the final. This is typically held in the final two weeks of May.
The tournament's current main sponsors are: Gazprom, Heineken, MasterCard, Nissan, PepsiCo, Sony, UniCredit, Adidas.
The competition attracts an extensive television audience, not just in Europe, but throughout the world. The final of the tournament has been, in recent years, the most-watched annual sporting event in the world. The 2013 final was the most watched final to date, drawing 360 million television viewers.
