WATCH: Zlatan brace returns AC Milan to Serie A summit

Ibrahimovic scored twice at Stadio San Paolo to take his tally for the Serie A season to 10 goals in six appearances before limping off 11 minutes from time.

The 39-year-old has been in inspired form for Milan since returning to the club in January, scoring 20 Serie A goals in 24 games – only Lazio's Ciro Immobile (23 in 27) and Juventus superstar Cristiano Ronaldo (29 in 24) have managed more in 2020.

But Ibrahimovic, who missed nearly a month of action after contracting coronavirus earlier in the season, may now be facing another spell on the sidelines after pulling up with an apparent hamstring issue against Napoli.

"We don't have too much information right now," Bonera said. "We will have to wait a few more days to see the extent of it."

Ibrahimovic's double made him the oldest player to score at least 10 goals in the first eight Serie A matchdays and put Milan two goals ahead against Napoli.

Dries Mertens pulled a goal back for the hosts but Napoli midfielder Tiemoue Bakayoko was sent off against his former club 165 seconds later and it was left to substitute Jens Petter Hauge to seal the win for Milan with his maiden top-flight goal.

Bonera, placed in charge of Milan due to head coach Stefano Pioli and various other backroom staff members being struck down by COVID-19, was pleased to come away with a win that moved the Rossoneri two points clear at the Serie A summit.

"This is evidently an important victory, one that shows we are on the right track," he said. "But it's really premature at the eighth round to talk about what might happen in May.

"I spoke to Pioli after the game and he was very happy and got to see all the lads in the dressing room, too." 

Milan had just 37 per cent of the ball but still managed seven attempts on target against Napoli, whom they had previously failed to beat away from home in the league since 2010.

But while being happy with the way 2020-21 is panning out, Bonera was keen to put his side's title aspirations into some perspective.

"We've learned from the past not to underestimate any opponent," he said. "I consider Napoli to be a great team - they were up against another great team in Milan, but there are so many games still to play. It's too early to say anything.

"There are squads who invested and were built to challenge for the Scudetto. In all honesty, we were not built to win straight away, but it does allow us to grow game by game and that might be an advantage in a way.

"We have a great squad at our disposal and are aware that we're up there now and want to stay there for as long as possible. This isn't a flash in the pan - we started this work a long way back."

Sixth-placed Napoli have lost two of their last three league matches and boss Gennaro Gattuso questioned his side's lack of hunger following this latest setback.

"I see football in such a completely different way to when I was a player," he said. "What I cannot accept, however, is to see my team without the fire in their belly. 

"At the first sign of difficulty now, we complain to the referee, complain to each other for it not being the right pass, complain to bad luck, we complain to everyone.

"Quality is not enough in football, we need to focus and fight for every result. I know what's wrong and it is not a coincidence that when we go into a really important game, we falter. We have to think as a team, with one mind, not as individuals."