Cristiano Ronaldo's first Champions League goals against Barcelona helped Juventus to a stunning 3-0 away win to top Group G. (More Football News)
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.
READ: Barca Hit New Low
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.
The Portuguese - meeting Lionel Messi for the first time as a Juve player - stuck to the script as he made the most of a generous early penalty award after Ronald Araujo appeared to get his body between man and ball in the box, dispatching his spot-kick down the centre of the goal.
It was two after just 20 minutes - the earliest Barca have ever conceded twice in a home Champions League game - with the defence this time afforded no excuse.
McKennie moved the ball wide to Juan Cuadrado and was allowed to meet the subsequent cross completely unimpeded with a close-range scissor kick.
Half-time then disrupted an improving home display and Barca were dealt a further blow five minutes after the restart as Clement Lenglet was deemed to have handled, following a VAR check, and Ronaldo was again clinical from 12 yards.
Messi's free-kick was nodded onto the top of the crossbar by Antoine Griezmann, who was denied a penalty due to offside as pressure again built on the Juve goal and Matthijs de Ligt dived in rashly.
A VAR call belatedly went Barca's way when Ronaldo bundled the ball onto an offside Leonardo Bonucci, seeing a fourth goal struck off, but it did not impact an eye-catching result.
What does it mean? LaLiga troubles translate
This was a standout win for Juventus, who are the first Italian team to score three times away from home against Barcelona, but the undoubted story was the continuation of the Blaugrana's problems.
Such issues had previously been restricted to the league - they could have become just the eighth team ever to win all six Champions League group games on Tuesday - yet this result undid their earlier impressive work in Europe.
A tricky last-16 draw is not what Koeman needs right now, although recent performances would suggest he will do well to make it that far.
Juve front two terrific
There are unlikely to be many more Messi v Ronaldo meetings, and CR7 was determined to steal the show, scoring with two of his three shots - all of which hit the target - as well as teeing up a further chance.
But strike partner Alvaro Morata was similarly impressive, providing a nuisance factor up front. The number nine contested a joint-team-high 13 duels and won three fouls.
Meanwhile, Messi had 11 shots without scoring.
Defensive difficulties
Barca's league defeats have come courtesy of defensive errors, with Lenglet the latest to fall foul of such a mistake in last weekend's defeat to Cadiz as he committed his first error leading to a goal in LaLiga since swapping Sevilla for Camp Nou.
Individual mistakes were the least of the hosts' concerns at the back this time, though, with the whole defence all over the place. Both Lenglet and Araujo were out of position for the second, while a lack of discipline was evidenced by Jordi Alba's booking for dissent.
What's next?
Barca host Levante in LaLiga on Sunday as they aim to belatedly get their campaign up and running. Juve also have work to do in Serie A as they visit Genoa earlier the same day.
