UEFA's new seeding system means Jose Mourinho faces the possibility of his Chelsea side being in the same group as his old team Real Madrid when the draw for the Champions League takes place in Monaco on Thursday.
The draw will be shown live on RTÉ Player and RTÉ News Now.
The new system will see the pot of top seeds made up of the champions Barcelona and seven other domestic champions from the leading European leagues - including Chelsea and Bayern Munich.
Real Madrid will be in pot two along with Arsenal, Manchester City and - pending their likely qualification - Manchester United. As English clubs cannot be drawn in the same group, it means there is more of a chance of Chelsea being drawn against Real.
UEFA's shake-up of its seeding system should refresh the competition as it sees five teams who would have been top seeds under previous rules now among the pot of second seeds.
It means too that the English clubs in pot two will themselves have a greater chance of facing one of the European powerhouses in the group stages than in previous years - Arsenal or the Manchester sides could find themselves up against Barca or Bayern.
It is the first time more for than a decade that Arsenal and Manchester United have not been top seeds.
Arsenal boss Arsene Wenger criticised the changes when they were announced by UEFA as "unnecessary and illogical".
He said at the time: "I believe it will just make the seedings useless. Logic is not being respected. Logic for me when you play in Europe is results in Europe.
"It will just make the seeding less interesting. Pot one will now have less significance."
UEFA's general secretary Gianni Infantino has defended the new system, saying it is right to give national domestic champions top seeding.
He said: "People had difficulties in understanding how the champion of a country is in a lower pot than the third-ranked in that country.
"This will give another dynamic with the draw and in the way the groups are composed.
"Football is about winning. It's about competition. It's about sporting merit.
"I think it's kind of a natural thing to give to those who have won a competition a special treatment like this."
The new system also means domestic champions with a lower co-efficient benefit - Dutch side PSV Eindhoven along with Juventus, Benfica, Paris St Germain and Zenit St Petersburg are all in pot one.
When does the draw start?
At 4.45pm Irish time in Monaco, though they may not get down to business right away. The ceremony includes the vote for, and presentation of, the 2014-15 UEFA Best Player in Europe Awards for men and women.
Remind us what the format is for the group stage?
The 32 teams will be drawn into eight groups of four, to play each other home and away between September and December. The top two teams from each group progress to the last 16 knock-out stages in February.
How will the draw be made?
The 32 teams will be split into four seeded pots with each group containing one from each pot.
Can teams from the same country be in the same pot?
Yes, they can.
Can teams from the same country be drawn together?
Not at this stage, no. Teams from the same association cannot be put in the same group.
Is there anything new in the draw format this season?
Yes. A new seeding system means Pot 1 will be comprised of the holders and the champions of the top seven associations: Spain, England, Germany, Italy, Portugal, France and Russia. As Barcelona are also Spanish champions, the eighth-ranked Holland receive the vacant seeding place.
So which teams are in Pot 1?
Pot 1 will be made up of: Barcelona, Chelsea, Bayern Munich, Juventus, Benfica, Paris St Germain, Zenit St Petersburg and PSV Eindhoven.
What about the other pots?
The other pots will be finalised following the play-off results on Wednesday night. Real Madrid, Atletico Madrid, Porto, Arsenal and Manchester City are already guaranteed to be in Pot 2. Manchester United would also be in Pot 2 if they beat Club Brugge.