A superb curling strike from Dries Mertens put the home side in front after half an hour and saw the Belgian draw level with Marek Hamsik as Napoli's all-time top scorer with 121 goals.

But Barca breached a well-drilled Napoli defence in the 57th minute when Griezmann fired in a Nelson Semedo cross.

The visitors ended the game with 10 men after Arturo Vidal was sent off late on for picking up two yellow cards in quick succession.

The two sides, who were facing each other for the first time, will meet again at the Camp Nou for the second leg on March 18 with Barca now firm favourites to progress despite having Vidal and Sergio Busquets suspended for the return.

Napoli coach Gennaro Gattuso was left frustrated at the result after his well-drilled defence largely stifled a quiet Lionel Messi and co.

"I think they barely grazed us tonight, they hardly had a single shot on goal," he told Sky Sport Italia.

"They could've been there all night and not scored, but we conceded after one single error. They didn't hurt us, it barely tickled."

Barcelona dominated possession from the first whistle but struggled to find their way through the well-organised Italians, who then struck with their first meaningful attack of the game.

Junior Firpo lost the ball to Piotr Zielinski and the midfielder pulled a pass across to the waiting Mertens, who took a touch just outside the box before curling in a landmark goal, his sixth in seven Champions League games this season.

But the Belgian limped off through injury early in the second half after a hefty tackle from Busquets, which earned the midfielder the yellow card that will rule him out of the second leg.

Barca soon equalised when Griezmann fired home from close range after a neat passing move from the visitors but Napoli responded with Lorenzo Insigne and Jose Callejon both being denied by excellent saves from Marc-Andre ter Stegen.

In the 89th minute, Vidal was booked for a foul on Mario Rui and was immediately shown a second yellow for butting heads with the defender in the aftermath.

With Sunday's La Liga Clasico against Real Madrid looming, Barca were also left with concerns over defender Gerard Pique, who limped off with an injury after falling heavily on his ankle.

"We'll see what problem he has, then we can confirm if he'll be available," said Barcelona coach Quique Setien.

On Vidal's sending off, he added: "I didn't see precisely what happened, but perhaps the referee was a bit harsh.

"A yellow card for the foul is one thing, but the second is too much. There are moments of tension that players who experience the game with his temperament can have."