The draw was held on 28 August 2014, 17:45 CEST, at the Grimaldi Forum in Monaco. The 32 teams were allocated into four pots based on their UEFA club coefficients at the beginning of the season, with the title holders being placed in Pot 1 automatically. They were drawn into eight groups of four containing one team from each of the four seeding pots, with the restriction that teams from the same national association could not be drawn against each other. Moreover, the draw was controlled for teams from the same association in order to split the teams evenly into the two sets of groups for maximum television coverage. The fixtures are decided after the draw. On each matchday, four groups play their matches on Tuesday, while the other four groups play their matches on Wednesday, with the two sets of groups alternating between each matchday. There are other restrictions: for example, teams from the same city in general do not play at home on the same matchday, and Russian teams do not play at home on the last matchday due to cold weather. On 17 July 2014, the UEFA Emergency Panel ruled that Ukrainian and Russian clubs would not be drawn against each other "until further notice" due to the political unrest between the countries. Therefore, Ukrainian club Shakhtar Donetsk and Russian club CSKA Moscow could not be drawn into the same group despite being in different pots.
Teams
Below were the 32 teams which qualified for the group stage, grouped by their seeding pot. They included 22 teams which entered in this stage, and the 10 winners of the play-off round.
Key to colours
Group winners and runners-up advanced to the round of 16
In each group, teams played against each other home-and-away in a round-robin format. The group winners and runners-up advanced to the round of 16, while the third-placed teams entered the Europa Leagueround of 32.
Tiebreakers
The teams were ranked according to points. If two or more teams were equal on points on completion of the group matches, the following criteria were applied to determine the rankings:
higher number of points obtained in the group matches played among the teams in question;
superior goal difference from the group matches played among the teams in question;
higher number of goals scored in the group matches played among the teams in question;
If, after applying criteria 1 to 4 to several teams, two or more teams still have an equal ranking, criteria 1 to 4 are reapplied exclusively to the matches between the teams in question to determine their final rankings. If this procedure does not lead to a decision, criteria 6 to 8 apply;
superior goal difference from all group matches played;
higher number of goals scored from all group matches played;
higher number of coefficient points accumulated by the club in question, as well as its association, over the previous five seasons.
Groups
The matchdays were 16–17 September, 30 September – 1 October, 21–22 October, 4–5 November, 25–26 November, and 9–10 December 2014. The match kickoff times were 20:45 CEST/CET, except for matches in Russia and one match in Belarus which were 18:00 CEST/CET. Times up to 25 October 2014 were CEST, thereafter times were CET.
