Matches may also be played on Tuesdays or Wednesdays instead of the regular Thursdays due to scheduling conflicts.
Format
The knockout phase involved 32 teams: the 24 teams which qualified as winners and runners-up of each of the twelve groups in the group stage, and the eight third-placed teams from the Champions League group stage.[1]
Each tie in the knockout phase, apart from the final, was played over two legs, with each team playing one leg at home. The team that scored more goals on aggregate over the two legs advanced to the next round. If the aggregate score was level, the away goals rule was applied, i.e., the team that scored more goals away from home over the two legs advanced. If away goals were also equal, then thirty minutes of extra time was played. The away goals rule was again applied after extra time, i.e., if there were goals scored during extra time and the aggregate score was still level, the visiting team advanced by virtue of more away goals scored. If no goals were scored during extra time, the tie was decided by penalty shoot-out. In the final, which was played as a single match, if scores were level at the end of normal time, extra time was played, followed by penalty shoot-out if scores remained tied.
The mechanism of the draws for each round was as follows:
In the draw for the round of 32, the twelve group winners and the four third-placed teams from the Champions League group stage with the better group records were seeded, and the twelve group runners-up and the other four third-placed teams from the Champions League group stage were unseeded. The seeded teams were drawn against the unseeded teams, with the seeded teams hosting the second leg. Teams from the same group or the same association could not be drawn against each other.
In the draws for the round of 16 onwards, there were no seedings, and teams from the same group or the same association could be drawn against each other.
Note: Between the 2004–05 and 2008–09 seasons, the competition was still known as the UEFA Cup, but is included as it followed a group stage—knockout phase format.