The UEFA Champions League is an annual club football tournament which was established in 1955. It is one of the most prestigious tournament in club football and is contested by the top teams from all over Europe. The tournament was first named as the European Cup and after the 1991-1992 season it was renamed as The Champions League. The Champions League Groups for the 2018-19 season are as follows:
| Group A | Group B | Group C | Group D |
| Atletico Madrid | FC Barcelona | Paris Saint-Germain | FC Porto |
| Borussia Dortmund | Tottenham Hotspur | Liverpool | FC Schalke 04 |
| Club Brugge | Inter Milan | Napoli | Galatasaray |
| AS Monaco | PSV Eindhoven | Red Star Belgrade | Lokomotiv Moscow |
| Group E | Group F | Group G | Group H |
| Bayern Munich | Manchester City | Real Madrid | Juventus |
| Ajax | Lyon | AS Roma | Manchester United |
| Benfica | Shakhtar Donetsk | Plzen | Valencia |
| AEK Athens | Hoffenheim | CSKA Moscow | Young Boys |
In its current format, The Champions League begins in early July with four knockout qualifying rounds and a playoff round. The 32 teams that qualify for the tournament are split into four seeded pots. The first pot comprises the UEFA Champions League winners, the UEFA Europa League winners and the domestic champions of the top six ranked associations in accordance with the access list. If either or both the titleholders are the domestic champions of one of the top six associations, the pot is completed with the champions of the next highest ranked associations. The other three pots are composed in accordance with the club coefficient rankings established at the beginning of the season. This is determined by the sum of all points won in the previous five years. In cases where clubs have identical five year coefficients, rankings are determined by coefficients in the recent season.
The draw will start with Pot 4, assigning each team from the pot into a group. This will eventually continue for Pot 3 then Pot 2 and Pot 1. No team can play a club from their own association and based on decisions taken by the UEFA Executive Committee, clubs from Russia and Ukraine must not be drawn in the same group due to the political unrest between the countries.
Moreover, the draw was controlled for teams from the same association in order to split the teams evenly into the two sets of four groups (A–D, E–H) for maximum television coverage. On each matchday, one set of four groups play their matches on Tuesday, while the other set of four groups play their matches on Wednesday, with the two sets of groups alternating between each matchday. The following pairings were announced by UEFA after the group stage teams were confirmed.
Real Madrid and Barcelona
Atletico Madrid and Valencia
Bayern Munich and Borussia Dortmund
Manchester City and Tottenham Hotspur
Juventus and Inter Milan
Paris Saint Germain and Lyon
Lokomotiv Moscow and CSKA Moscow
Porto and Benfica
Manchester United and Liverpool
Napoli and Roma
Schalke and Hoffenheim
Ajax and PSV Eindhoven
If a paired club is drawn for example in groups A, B, C or D, the other paired club once drawn will automatically be assigned to one of the groups E, F, G or H.
Each club plays one home and one away match against each other club in its group. Three points are awarded for a win, one point for a draw and none for a defeat. The top two teams in each group will advance to the knockout stage, while the third placed team drops into The Europa League. The clubs that finish the group stage in fourth position are eliminated.
