Manchester United and Liverpool have both been handed stiff tests in the Champions League group stages.
Three-time winners United will need to come out of a group containing last year's runners-up PSG and semi-finalists RB Leipzig as well as Turkish competition newcomers İstanbul Başakşehir.
Liverpool, winners of a sixth crown in 2019, will face that year's semi-finalists Ajax Amsterdam, Italian side Atalanta, who made the quarter-finals in 2020, and Danish debutants Midtjylland.
Manchester City (Porto, Olympiacos and Marseille) and Chelsea (Sevilla, Krasnodar, Rennes) look to have slightly more manageable tasks.
Lionel Messi and Cristiano Ronaldo will renew their Champions League rivalry after their teams Barcelona and Juventus, who met in the 2015 final, were drawn in Group G along with Dynamo Kiev and Hungarian side Ferencvaros.
The draw, held at a television studio in Geneva, produced several other high-profile clashes.
Defending champions Bayern Munich must face Diego Simeone's Atletico Madrid after they were drawn together in Group A alongside Salzburg and Lokomotiv Moscow.
Group B will see Real Madrid, who hold a record 13 European Cup titles, face Inter Milan, Shakhtar Donetsk and Borussia Monchengladbach.
Zenit St Petersburg are top seeds in Group F, where they will take on Borussia Dortmund, Lazio and Club Brugge.
Bayern Munich's Robert Lewandowski was UEFA men's player of the year while Chelsea's Danish striker Pernille Harder (formerly Wolfsburg) was women's player of the year.
Manchester City's Kevin de Bruyne was the only non-Bayern representative to win a men's individual award, being voted midfielder of the year.
The opening Champions League group fixtures will take place on October 20 and 21, with the scheduling set to be confirmed on Friday evening.
RTÉ Sport will broadcast a live game each match-week Tuesday.
The 2021 Champions League final is due to be held at the Ataturk Stadium in Istanbul on May 29.
Group A: Bayern Munich, Atletico Madrid, Salzburg, Lokomotiv Moscow
Group B: Real Madrid, Shakhtar Donetsk, Inter Milan, Borussia Mönchengladbach
Group C: Porto, Manchester City, Olympiacos, Marseille
Group D: Liverpool, Ajax, Atalanta, Midtjylland
Group E: Sevilla, Chelsea, Krasnodar, Rennes
Group F: Zenit, Dortmund, Lazio, Bruges
Group G: Juventus, Barcelona, Dynamo Kiev, Ferencváros
Group H: Paris Saint-Germain, Manchester United, Leipzig, İstanbul Başakşehir
Group stage dates (Tue/Wed)
Matchday 1: 20/21 October
Matchday 2: 27/28 October
Matchday 3: 3/4 November
Matchday 4: 24/25 November
Matchday 5: 1/2 December
Matchday 6: 8/9 December
Men's player of the season: Robert Lewandowski (Bayern Munich)
Coach of the season: Hans-Dieter Flick (Bayern Munich)
Goalkeeper of the season: Manuel Neuer (Bayern Munich)
Defender: Joshua Kimmich
Midfielder: Kevin de Bruyne (Manchester City)
Forward: Robert Lewandowski (Bayern Munich)
Women's player of the season: Pernille Harder (Chelsea, ex Wolfsburg)
Coach of the season: Jean-Luc Vasseur (Lyon)
Goalkeeper of the season: Sarah Bouhaddi (Lyon)
Defender: Wendie Renard (Lyon)
Midfielder: Dszenifer Marozsan (Lyon)
Forward: Pernille Harder