What is each club's pedigree? Who are their key players, new faces and ones to watch? UEFA.com has all the answers.
Article top media content
UEFA coefficient ranking (end of 2018/19): 11
How they qualified: UEFA Champions League winners
European Cup best: winners x6 (1977, 1978, 1981, 1984, 2005, 2019)
Last season: winners (beat Tottenham 2-0 in the final)
Group stage last season: Group C runners-up – W3 D0 L3 F9 A7 (v Paris, Napoli and Crvena zvezda)
In: Harvey Elliott (Fulham), Sepp van den Berg (Zwolle), Adrián (West Ham)
Out: Daniel Sturridge (released), Alberto Moreno (released), Danny Ings (Southampton)
Coach: Jürgen Klopp
Spent his playing days as a central defender in Germany's lower leagues before being named Mainz coach in 2001. Dortmund came calling in 2008, Klopp leading BVB to back-to-back Bundesliga titles and then the UEFA Champions League final in 2013. Took over two years later at Liverpool, who he guided to the UEFA Europa League final in 2016 and UEFA Champions League glory last season (after losing in the 2018 decider).
Key player: Virgil van Dijk
The 28-year-old kept more clean sheets than any defender in Europe's top five leagues last season and capped a wonderful campaign with a man of the match performance in the UEFA Champions League final. The linchpin of the Liverpool defence is the UEFA Men's Player of the Year.
One to watch: Rhian Brewster
The 2017 FIFA Under-17 World Cup Golden Boot winner, who was on the bench for last season's UEFA Champions League final, can seize an opening in the squad following Daniel Sturridge's summer departure. Jürgen Klopp says: "Brewster is a top striker; he is a top talent and I have told him already that he has an important role this year."
UEFA coefficient ranking (end of 2018/19): 15
How they qualified: second in Italy
European Cup best: round of 16 x2 (2012, 2017)
Last season: group stage (third place), #UEL quarter-finals
Group stage last season: third in Group C – W2 D3 L1 F7 A5 (v Paris, Liverpool, Crvena zvezda)
In: Kostas Manolas (Roma), Eljif Elmas (Fenerbahçe), Hirving Lozano (PSV), Fernando Llorente (Tottenham)
Out: Amadou Diawara (Roma), Raúl Albiol (Villarreal), Carlos Vinícius (Benfica)
Coach: Carlo Ancelotti
A two-time European Cup-winning midfielder with Milan and Serie A champion on three occasions with the Rossoneri and Roma, the Italian has been even more successful as a coach. Two UEFA Champions League victories with Milan and another at Real Madrid have been embellished with league titles in Italy, England, France and Germany.
Key player: Arkadiusz Milik
Having suffered two cruciate ligament injuries since joining in summer 2016, the Poland striker scored 20 goals in all competitions last season. The clinical, all-round forward has formed a prolific attacking trident with Lorenzo Insigne and Dries Mertens, making Napoli an attractive team to watch.
One to watch: Eljif Elmas
Capped by North Macedonia at 17 as Turkey looked to secure his services, the midfielder joined Napoli in July after impressing at Fenerbahçe. Still only 19, the Partenopei clearly expect him to shine in the future, having handed him a contract until 2024.
UEFA coefficient ranking (end of 2018/19): 29
How they qualified: Austrian champions
European Cup best: group stage (1994/95)
Last season: play-offs (lost on away goals, 2-2 on aggregate, to Crvena zvezda), #UEL round of 16
In: Rasmus Kristensen (Ajax), Maximilian Wöber (Sevilla)
Out: Hannes Wolf (RB Leipzig), Stefan Lainer (Mönchengladbach), Xaver Schlager (Wolfsburg), Diadie Samassékou (Hoffenheim)
Coach: Jesse Marsch
As a player, he was a midfielder for DC United, Chicago and Chivas and won two USA caps and three MLS Cups. Coached in that league with Montreal and New York RB before taking an assistant role at Leipzig last season. Replaced Marco Rose at Salzburg in June.
Key player: Andreas Ulmer
Salzburg have made their name in recent seasons by bringing in a wealth of attacking talent and playing free-flowing football, but captain Ulmer has been a mainstay at the other end. Now 33, the full-back has won ten Austrian titles and played more than 350 games for the club.
One to watch: Erling Braut Håland
Son of ex-Norway midfielder Alf Inge Håland, the tall striker scored nine in a FIFA Under-20 World Cup finals game against Honduras in May 2019 and followed that up with two hat-tricks in his next four outings for Salzburg.
UEFA coefficient ranking (end of 2018/19): 60
How they qualified: Belgian champions
European Cup best: group stage x2 (2003, 2012)
Last season: #UEL round of 32 (lost 4-1 on aggregate to Slavia Praha)
In: Theo Bongonda (Zulte Waregem), Ianis Hagi (Viitorul), Patrik Hrošovský (Viktoria Plzeň)
Out: Leandro Trossard (Brighton), Ruslan Malinovskyi (Atalanta), Joseph Aidoo (Celta Vigo)
Coach: Felice Mazzù
A physical education teacher who had no significant playing career, Mazzù started coaching in the lower leagues before making the step up to Tubize in 2009, before three years at RWS Bruxelles then six at his hometown club Charleroi. Took over at Genk this summer.
Key player: Sander Berge
The towering holding midfielder has earned rave reviews in the two and a half years since joining from Vålerenga. Still only 21, Berge already has 14 caps for Norway and has been in the international setup for more than two years.
One to watch: Ianis Hagi
The son of the 'Maradona of the Carpathians' Gheorghe Hagi, Ianis was classy at the 2019 Under-21 finals, playing a key role as Romania reached the semi-finals. Left Viitorul for Genk shortly after the tournament having scored 14 goals in his final season in his home country.
Did you know?
- Holders Liverpool have reached the last two finals and are in the group stage for the 12th time.
- Liverpool reached last season's knockout rounds thanks to a 1-0 home win against Napoli on matchday six.
- Salzburg are making their second group appearance – and their first since their debut in 1994/95.
- Napoli beat Salzburg in last season's UEFA Europa League round of 16, winning 3-0 at home and going through despite a 3-1 second-leg loss in Austria.
- Genk have never played any of their three Group E opponents.