Juventus boss Massimiliano Allegri admitted his team were well below their best at Napoli despite taking a giant leap towards the Serie A title.

The Bianconeri extended their lead at the top of Serie A to 16 points with a dramatic 2-1 victory over their nearest rivals.

Goalkeeper Alex Meret's red card midway through the first half was a major blow for Napoli, with leading scorer Arkadiusz Milik making way so that back-up keeper David Ospina could come on. Ospina's first task was to pick the ball out of his net after Miralem Pjanic scored from the resulting free-kick.

Emre Can headed Juventus into a two-goal lead before half-time but Pjanic was sent off early in the second half, giving a glimmer of hope to Napoli who dominated the game thereafter.

"I should have substituted him (Pjanic) off before, because he was at risk. After his sending off, in fact, we lost our way and Napoli grew," Allegri told the club's official website.

Soon after the red card Jose Callejon reduced the deficit and Napoli were presented with the chance to equalise with seven minutes remaining when they were awarded a penalty. However, Lorenzo Insigne's spot-kick hit a post and rolled across the face of the goal and to safety.

"We conceded a penalty, Insigne made a mistake and in that moment the game was finished," said Allegri. "We can say that we are five and half victories away from the title. Now we will rest and then we will prepare for our next fixtures."

Allegri wants his team to be much better when they play Atletico Madrid in the second leg of their Champions League clash later this month, with Juventus looking to overturn a 2-0 deficit in Turin in the last-16 tie.

He said: "We were imprecise in our passes but when we played against Napoli, we did well. We need to be better technically and, in the decision making, in the next few games.

"Against Atletico we have the quality to play with serenity and without fear. That evening we need to have patience, be lucid and calm. If it's 0-0 in the 70th minute, I don't want it to be said that we are eliminated. In the first leg we conceded two goals in five minutes."

Napoli boss Carlo Ancelotti was pleased with how his team responded to the setback of Meret's early red card, but criticised the referee for not using VAR to check the decision.

"I'm happy with the squad reacted to the adversity. We conceded right after the sending off, making things extremely tough for us," Ancelotti told the club's official website.

"We penned Juventus in during the second period. I saw great character from the team.

"It is very controversial. I do not think Meret touched (Cristiano) Ronaldo, but that's not the point. Other factors could have been considered – like if Ronaldo could have got to the ball.

"The referee could have gone to VAR – why else do we have it?"