All rounds in the knockout phase, including the final, are played under the knockout system, whereby each club plays each opponent twice, in home and away matches.
The UEFA administration may decide that a tie be played in one leg, if circumstances so require, and will set the principles for determining the winner accordingly.
The team that scores the greater aggregate of goals in the two matches qualifies for the next stage, or, in the case of the final, is the winner of the competition. Otherwise, Article 18 applies.