Click the links for full matchcasts, reports and ratings.
Chelsea found a new Champions League hero as Brazilian Oscar scored twice for the holders in a 2-2 draw against Juventus.
Danish newcomers Nordsjaelland got a taste of the challenges to come when they were beaten 2-0 by Ukraine's Shakhtar Donetsk.
Bayern Munich banished some demons in their first European fixture since their bitter final defeat by Chelsea in May with victory over Valencia.
BATE Borisov, the champions of Belarus, earned a first ever group stage win when they beat Lille 3-1 in France.
Barcelona had yet another commanding performance from Lionel Messi to thank for a 3-2 win over Spartak Moscow.
Celtic drew 0-0 at home to Benfica on their return to the group phase for the first time since 2008.
Manchester United, with plenty to prove after last season's woes, began with an unconvincing 1-0 victory over Galatasaray.
CFR Cluj impressed in a 2-0 victory at Portuguese side Braga with Rafael Bastos returning to score twice against his former club.