Piotr Zielinski put the visitors ahead in the first half, before Ferran Torres leveled things for Barcelona on the hour mark.
Despite dominating the latter stages, Barcelona couldn’t find a winner, and although the away goals rule is no longer in place, Napoli will be very happy to head into the second leg in Italy next week.
Pierre-Emerick Aubameyang got his first Barcelona start, with Adama Traore and Ferran Torres also selected as Xavi trusted the former Premier League trio.
With just under half an hour of play, two of them combined to create a huge chance. Aubameyang raced behind and played inside for Torres who was on goal but sent his effort high and wide when he had to score.
He made it regret even more less than a minute later when Napoli took the lead. Elif Elmas brilliantly managed to turn and return the ball to Zielinski in the box and although his first shot was saved by Marc-Andre ter Stegen, he was on hand to send the rebound into the roof of the net.
Aubameyang wrapped up an effort from range and Torres couldn’t head a header, as Barcelona entered the break behind after a disappointing display.
Barcelona got level with an hour in the game, largely thanks to a VAR review. The home side appealed for a penalty after Traore’s cross grazed Juan Jesus’ hand and although the referee initially dismissed the appeals he looked to the replays and came back to point for the spot.
Torres put his previous failures behind him to prevail and coolly slip past Alex Meret, giving Barcelona a much-needed equaliser.
Ousmane Dembele was brought in by Xavi, although his ongoing contract situation meant many home fans booed his every contact.
Barcelona dominated possession late on as Napoli grew tired and settled for what they had. Torres missed another huge chance two minutes from time after a fine flick from Pedri, the former Man City man curling a close-range effort well over the bar.
Dembele then fired a superb ball into the face of goal, but he didn’t fall for both Barcelona shirts at the back post, and Luuk de Jong sent a kick wide wide shortly after as the hosts increased the pressure.
There was not to be a late winner, and Napoli will certainly be the happier of the two teams heading into the second leg.