Home advantage in sport is well documented in the literature. Factors related to the location and venue, and referee’s behaviour for psychological reasons are usually considered to be the causes of home advantage. Many knock-out competitions are set to an odd number of matches. However, in some sports (for example, football, handball and table tennis) the number of matches is even. Thus, the decision to be made is how to choose the venue of the matches since it is usual to play the same number of matches in each venue. Home advantage effect is especially relevant in football where, for instance, 48 per cent of the matches played in the Spanish First Division between seasons 2000–2001 and 2010–11 have been won by the local team, while the away percentage of winning was below 28 per cent. The UEFA has set that the second match has to be played in the best classified venue in the round-robin stage in the UEFA Champions League, but to the best of our knowledge there is no paper that has analysed this issue. This chapter aims to fill this gap in the literature by analysing most best-of-two rounds played in UEFA competitions.