Tottenham have been handed a nightmare Champions League draw after they were grouped with defending Champions Real Madrid and German side Borussia Dortmund in today's draw in Nyon.
Spurs, runners-up in the Premier League May also take on as Cyprus side APOEL in Group H.
Chelsea will face Atletico Madrid in Group C in a draw which brings Diego Costa's ongoing exile into renewed focus.
Costa joined Chelsea from Atletico in July 2014 and has been an unauthorised absentee from London this summer as he agitates for a move back to his former club. The situation is complicated by a transfer embargo which prevents Atletico from registering new players until January.
Roma and Qarabag, the first Azerbaijan side to reach the group stages, are also in Group C.
Scottish champions Celtic, play-off winners over Kazakhstan's Astana, are also in a challenging pool, against Bayern Munich, Paris St Germain and Anderlecht in Group B.
Manchester United, who qualified by winning the Europa League in May, received a favourable draw in Group A alongside Benfica, Basle and CSKA Moscow.
Five-time winners Liverpool, who advanced via the play-offs with victory over Hoffenheim will also be pleased with their draw and will play Spartak Moscow, Sevilla and Maribor in Group E.
Manchester City will face Shakhtar Donetsk, Napoli and Feyenoord in Group F.
The final takes place at the NSK Olimpiyskyi in Kiev on May 26, 2018.
Real Madrid won Europe's elite club competition in Cardiff in June, becoming the first team in the Champions League era to win back-to-back titles.
Their draw with Tottenham reunites Gareth Bale and Luka Modric with their former club.
The draw was made at the Grimaldi Forum in the Principality by Francesco Totti and Andriy Shevchenko, the former Chelsea striker and an ambassador for the 2018 final in his native Ukraine.
Teams from the same association cannot face each other in the group stage.
It is only the second season that five clubs from one nation were in the group stage, after Spain had five representatives in 2015-16.
Chelsea return to the competition after a season's absence after winning the English title under Antonio Conte.
Manchester United are back under Jose Mourinho, a Champions League winner in 2004 with Porto and 2010 with Inter Milan, after being knocked out on in the group stage in 2015-16.
Juventus, runners-up in Cardiff in June, face Barcelona, Olympiacos and Sporting Lisbon in Group D.
Group G features Monaco, Porto, Besiktas and RB Leipzig.
Group A
Benfica
Manchester United
Basle
CSKA Moscow
Group B
Bayern Munich
Paris St Germain
Anderlecht
Celtic
Group C
Chelsea
Atletico
Roma
Qarabag
Group D
Juventus
Barcelona
Olympiakos
Sporting
Group E
Spartak Moscow
Sevilla
Liverpool
Maribor
Group F
Shakhtar Donetsk
Manchester City
Napoli
Feyenoord
Group G
Monaco
Porto
Besiktas
RB Leipzig
Group H
Real Madrid
Borussia Dortmund
Tottenham
Apoel
