Barcelona avoided a shock at home to Spartak Moscow as Lionel Messi scored twice in the final 19 minutes to earn them a 3-2 Champions League victory.
Cristian Tello put Barca ahead in the 14th minute but an own goal from Dani Alves and a second-half strike from Borges Romulo saw Spartak turn the game on its head and leave the Nou Camp shellshocked.
Messi, as he so often is, was Barca's hero though as he scored in the 71st and 80th minutes to leave Tito Vilanova's men top of Group G.
In Group E, Henrikh Mkhitaryan scored twice to give Shakhtar Donetsk a 2-0 win over FC Nordsjaelland, while in Group F, Bayern Munich and BATE Borisov both started their campaigns with victories.
Bayern beat Valencia 2-1 with Bastian Schweinsteiger and Toni Kroos on the scoresheet for the Germans with the Spanish side pulling a goal back late on through Nelson Haedo Valdez.
Bayern also missed a last-minute penalty through Mario Mandzukic after Valencia defender Adil Rami had been sent off.
Belarusian champions BATE saw off Lille with a blistering first-half display.
Alexander Volodko swept the visitors in front with just six minutes on the clock with a superb lofted finish over Mickael Landreau, and further goals from Vitaly Rodionov and Edgar Olekhnovich effectively ended the contest before half-time.
Aurelien Chedjou reduced the deficit just before the hour mark but the French side could not get any closer.