Barcelona's poor domestic form carried over into their European campaign as they were denied top spot by Cristiano Ronaldo and Juventus.
Cristiano Ronaldo's first Champions League goals against Barcelona helped Juventus to a stunning 3-0 away win to top Group G.
The Bianconeri had lost 2-0 in Turin in the reverse fixture as an absent Ronaldo recovered from coronavirus, meaning they would have to improbably better that result at Camp Nou to leapfrog their hosts.
But Barca's recent defensive woes continued on Tuesday and two Ronaldo penalties - one contentious, the other routine - and a Weston McKennie volley carried Juve to a deserved victory.
Ronaldo had not previously netted in five European matches against the Blaugrana yet delighted in piling further pressure on under-fire home coach Ronald Koeman, whose side are ninth in LaLiga.