Antoine Griezmann’s equaliser cancelled out a fine opener from Napoli’s Dries Mertens to give Barcelona a 1-1 draw and the upper hand in their Champions League last-16 tie.

Mertens had made the most of the Italian club’s solid start to curl home an effort after 30 minutes. However, after the midfielder was forced off with injury following a heavy challenge from Sergio Busquets, Barcelona drew level when Griezmann lashed the ball in from close range.

Barça finished with 10 men after Arturo Vidal was shown two quick yellow cards for a tackle on Mário Rui and then pushing his head into the face of the Napoli man during the closing stages.

“It’s a positive result for us overall,” said the Barcelona coach, Quique Setien. “We controlled most of the game, but we lacked something in the final third against such an organised defence by Napoli.

“After the equaliser, they opened up a little and we were able to hurt them more. They played very well and it was not easy, so a score draw is fine going into the second leg.”

Lionel Messi, who scored four goals in the 5-0 win over Eibar which put Barcelona top of LaLiga, sent an early chance over before Napoli made a breakaway count as Mertens swept them in front. Piot Zielinski won possession from Junior Firpo and charged down the right before cutting the ball across the edge of the Barcelona area, Mertens took a touch before curling a wonderful finish over a static Marc André ter Stegen and into the top corner – a goal which made the Belgian Napoli’s joint record scorer, level on 121 goals with Marek Hamsik.

Arturo Vidal reacts after referee Felix Brych showed him a second yellow card. Photograph: Filippo Monteforte/AFP via Getty Images

Barcelona looked for a swift response before half-time but failed to stretch the home defence or test the goalkeeper David Ospina. The Partenopei could have been further ahead after 42 minutes when a free-kick was only partial cleared, Fabian Ruiz fed Jose Callejon and his cross was fired just wide by centre-back Kostas Manolas.

They came out with more intensity at the start of the second half, too. Busquets caught Mertens with a high tackle which led to a yellow card and the Belgian eventually hobbled off, to be replaced by Arkadiusz Milik in the 54th minute.

Napoli continued to be pushed back by Barcelona’s press and Griezmann equalised after 57 minutes. Nélson Semedo beat the offside trap from Busquets’ pass when he darted into the right side of the area and crossed for the French World Cup winner to smash the ball in from close range.

Napoli, who finished second in Group E behind Liverpool, soon threatened again. Their captain, Lorenzo Insigne, weaved his way into the left of the Barça area and forced Ter Stegen into a low save. The German was alert again to come off his line and block from Callejon. At the other end Messi looked to get on the end of an exchange with Vidal and collided with Ospina as the Napoli keeper made a brave save, which saw both players need treatment.

Samuel Umtiti headed over a corner from Messi before Vidal saw red, meaning he will be suspended for the return at the Camp Nou next month. The Barça defender Gerard Piqué also limped off during stoppage time with what looked like an ankle problem.

Napoli’s coach Gennaro Gattuso felt his side had missed an opportunity to give themselves more of a foothold in the tie. “Barcelona struggled because we were very careful. We did well as a team to play together like this,” he said.

“I am disappointed because we made one mistake and they made the most of it. We suffered tonight, tactically we were almost perfect, but we could have done better and been more clinical.”