Manchester City have been handed a tough Champions League group stage draw against Juventus, Sevilla and Borussia Monchengladbach.
City, who also dealt with tough draws in the past four seasons of the Champions League, were selected in Group D with last season's finalists and the Europa League champions.
Holders Barcelona, meanwhile, are in Group E alongside Roma, who finished second in Serie A last season, Bayer Leverkusen and BATE Borisov.
Barcelona lifted the trophy for the fifth time in their history after Luis Enrique's side beat Juventus 3-1 in June's final.
Barca, who also won La Liga and the Copa del Rey last season, are looking to become the first club to retain the Champions League.
Manchester United's return to the competition under manager Louis van Gaal sees them take on Bundesliga runners-up Wolfsburg and Eredivisie champions PSV Eindhoven in Group B, along with CSKA Moscow.
Arsenal also face a tough task in Group F against Bayern Munich, who have eliminated the Gunners from the competition in two out of the past three seasons -- but have more straightforward opposition from Greek side Olympiakos -- who are in the middle of a match-fixing scandal -- and Dinamo Zagreb from Croatia.
Real Madrid were drawn against Ligue 1 champions Paris Saint-Germain in Group A along with Shakhtar Donetsk and Malmo, where PSG's Swedish striker Zlatan Ibrahimovic began his career.
Real forward Cristiano Ronaldo said: "It will be tough as I think this group is strong, but we are going to do the same as before and try to qualify and the win the Champions League."
Chelsea boss Jose Mourinho will have a return to former side Porto, whom he took to Champions League glory in 2004, and his side should have little trouble advancing from Group G with Dynamo Kiev and Maccabi Tel Aviv.
A few hours after the draw, UEFA released a complete schedule of fixtures on their website.
Matchday 1: Sept. 15, 16
Matchday 2: Sept. 29, 30
Matchday 3: Oct. 20, 21
Matchday 4: Nov. 3, 4
Matchday 5: Nov. 24, 25
Matchday 6: Dec. 8, 9