Messi lifted the European Cup four times with Barca, but will now be out to win the trophy with his new club PSG in a star-studded squad also featuring the likes of Neymar and Kylian Mbappe.
As for Barca, they must move on and rebuild amid great financial pressure – but with the likes of Sergio Aguero, Memphis Depay, Antoine Griezmann, Pedri and Ansu Fati, there is more than enough quality to trouble plenty of Europe’s top sides this term.
With the Champions League group-stage draw set to be held this week, here are the potential opponents for Barca fans to watch out for in Pots 1-4…
Who can Barcelona face in the Champions League draw?
Pot 1: Chelsea, Villarreal, Atletico Madrid, Bayern Munich, Inter Milan, Lille, Sporting Libson, Manchester City
Barca cannot be drawn against Villarreal or Atletico given Uefa rules state two teams from the same association cannot face each other at this stage.
That means Barca will face one of Chelsea, Man City, Bayern, Inter, Lille or Sporting.
Pot 2:Real Madrid, Barcelona, Juventus, Manchester United, PSG, Liverpool, Sevilla, Borussia Dortmund
Barca are seeded in Pot 2, so will not face any of the seven other teams.
Pot 3: FC Porto, Ajax, RB Leipzig, Atalanta, Zenit, Benfica
Two teams are yet to be confirmed but Barcelona will be able to face any of the teams from Pot 3.
Pot 4:Club Brugge, Young Boys, AC Milan, Malmo, Wolfsburg.
Three teams are yet to be confirmed but Barcelona will be able to face any of the teams from Pot 4.
Pot 3 or 4 TBC:Besiktas, Dynamo Kyiv, RB Salzburg/Brondby, Monaco/Shakhtar Donetsk, Dinamo Zagreb/ Sheriff Tiraspol