The Italian champions, who have lifted the European Cup twice, should give Chelsea a stern test on September 19 before Roberto Di Matteo's side face Danish newcomers FC Nordsjaelland and Ukrainian champions Shakhtar Donetsk.
An intriguing series of games is in prospect in Group D with nine-times European champions Real Madrid joined by English champions Manchester City, Dutch league winners Ajax Amsterdam and German champions Borussia Dortmund.
Bayern Munich, who lost to Chelsea in last season's final on penalties in their own Allianz Arena stadium, will face Valencia, Lille and BATE Borisov of Belarus in Group F.
Chelsea's club secretary David Barnard, in Monaco for the draw told reporters: "It is not going to be easy. Manchester United thought they had an easy passage last season and went out early. You cannot afford to make that mistake. We will respect all our opponents and take nothing for granted."
Real director Emilio Butragueno told Spanish television His team had not had much luck after being drawn with Manchester City, Ajax and Dortmund.
"It's a very tough group, every game will be very tight with a lot of tension," he said. "We need to prepare very well. City are a very strong team after an enormous investment in recent years and they will be a rival of the highest level."
Manchester City, regarded as the richest club in the world following the hundreds of millions invested in it by the club's Arab owners over the last four years, failed to negotiate the group stage in their first Champions League campaign last season.
The English champions have a tough task again, travelling to Real in their first game on Sept. 18 before hosting Dortmund.
"I think it is the hardest group of them all with the champions of Spain, the Netherlands and Germany," Manchester City club ambassador Patrick Vieira said.
"But this is what the Champions League is all about. You have to play these teams and beat them if you want to win it. And we want to win it."
Bayern Munich, who also finished runners-up to Dortmund in the Bundesliga last season, face Valencia, who they beat on penalties in the 2001 Champions League final, Lille and BATE.
"I see Valencia as our strongest opponents in this group, but in any case its our duty to reach the quarter-finals, preferably by winning the group," Bayern captain Philipp Lahm told reporters.
Barcelona, the strong favourites last year until they lost to Chelsea in the semi-finals, face their old rivals Benfica, Spartak Moscow and Celtic.
The rivalry between Barcelona and Benfica goes back to the early days of European club football and the 1961 final when Benfica beat Barcelona 3-2 in Berne to win the first of their two European Cups, a game still remembered as a classic.
Barca midfielder Andres Iniesta, in Monaco and named as UEFA's Best Player in Europe last season, told guests in the auditorium: "The Champions League is an incredibly di
