Four English clubs will find out their Champions League group stage opponents when the draw takes place on Thursday.
Manchester City will be in pot one, Manchester United and Tottenham Hotspur in pot two, while Liverpool will be given either pot two or three.
The draw takes place at the Grimaldi Forum in Monaco at 17:00 BST.
Twenty-six clubs qualified directly for the group stages, with six still to come via the play-offs after the second legs are completed on Wednesday.
How does it work?
The Champions League and Europa League winners make it into pot one, alongside the champions in each of the six highest-ranked nations.
It means there are three Spanish sides among the top seeds this season because Real Madrid won a third successive Champions League, Atletico Madrid were crowned Europa League winners and Barcelona clinched the La Liga title.
The rest of the pots are decided by club coefficients – a ranking determined by how well a club has done in Europe over the past five years, and also how their association has performed.
Liverpool will make it into pot two if Benfica, the only side with a higher coefficient than them in the play-offs, do not qualify. The Portuguese side head to PAOK of Greece on the back of a 1-1 draw at home in the first leg.
One club from each pot will drawn to make up eight groups of four teams. Clubs from the same nation cannot be drawn together at this stage.
Pot one: Real Madrid, Atletico Madrid, Barcelona, Bayern Munich, Manchester City, Juventus, Paris St-Germain, Lokomotiv Moscow.
Pot two: Borussia Dortmund, Porto, Manchester United, Shakhtar Donetsk, Napoli, Tottenham Hotspur, Roma.
Pot three: Schalke, Lyon, Monaco, CSKA Moscow.
Pot four: Club Brugge, Galatasaray, Inter Milan, Hoffenheim.
To be decided: Liverpool, Valencia, Viktoria Plzen, plus six play-off winners.
Play-off first-leg results: Ajax 3-1 Dynamo Kiev, Vidi 1-2 AEK, Young Boys 1-1 Dinamo Zagreb, Benfica 1-1 PAOK, BATE 2-3 PSV, Red Star Belgrade 0-0 Salzburg.
When does the football start?
The first Champions League group stage games take place on 18 and 19 September, with clubs playing the last of their six matches on 11 or 12 December.
The knockout rounds begin in February, with the tournament concluding with the final at Atletico Madrid’s Wanda Metropolitano on 1 June, 2019.