Last season saw Bayern Munich lift the Champions League trophy, whereas, Spanish club Sevilla won the Europa League.
The Champions League will start from October 20 onwards and the Europa League will begin on October 22.
Here are the complete details.
The teams will be split into four pots, with pot one containing the holders, the Europa League winners and champions of the six highest-ranked countries.
Pots two, three and four are determined by UEFA's club coefficient rankings.
Six teams will join the already qualified 26 sides via the play-off ties.
No team can be draw against another from their own association.
Pot one: Bayern Munich, Sevilla, Real Madrid, Liverpool, Juventus, Paris St-Germain, Zenit St Petersburg, Porto.
Pot two: Barcelona, Atletico Madrid, Manchester City, Manchester United, Shakhtar Donetsk, Borussia Dortmund, Chelsea, Ajax.
Pots three or four: RB Leipzig, Inter Milan, Lazio, Atalanta, Lokomotiv Moscow, Marseille, Club Brugge, Borussia Monchengladbach, Istanbul Basaksehir, Rennes.
Six teams will be added to this group before the pots are split.
The 48 teams will be split into four pots. This will be determined by their club coefficient rankings - to form 12 groups.
In some cases, where associations have two or more teams involved in the draw, they may be paired so that they play with different kick-off times.
However, no team can be draw against another from their own association.
Champions League matchdays: Matchday one: October 20/21, matchday two: October 27/28, matchday three: November 3/4, matchday four: November 24/25, matchday five: December 1/2, matchday six: December 8/9.
Europa League matchdays: Matchday one: October 22, matchday two: October 29, matchday three: November 5, matchday four: November 26, matchday five: December 3, matchday six: December 6.
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