'Emotional' Sarri calls for Napoli calm

"Mentally, this is only a confirmation for us and it will give us a spur. But we have to be mindful that that is all it will give us," Sarri told reporters.

Yet Sarri, described by two-goal midfielder Dries Mertens as a "great coach", has every reason to be smiling after just two games of his maiden Champions League campaign.

Napoli fans had not been treated to Champions League football since 2013, when a side led by Walter Mazzarri were eliminated behind Borussia Dortmund and Arsenal.

But after a one-sided performance, even Benfica coach Rui Vitoria had to concede defeat.

"Napoli are a quality side," said Vitoria. "They capitalise on the least mistakes, are strong in possession and press up high.

"They're changing the philosophy of Italian football."

The San Paolo stadium was jumping in celebration at half-time after Slovakian international Marek Hamsik hit his 101st goal for the club when he was on hand to head Faouzi Ghoulam's corner past Julio Cesar on 20 minutes.

Napoli had restricted the visitors to two early shots by Kostas Manoglou that Napoli 'keeper Pepe Reina did well to keep out.

But in the space of 11 second-half minutes Napoli hit three quickfire goals to all but wrap up their second successive win after a come-from-behind 2-1 win at Dinamo Kiev a fortnight ago.

When Lisandro Lopez hauled down Mertens just inside the area, the Belgian's superb curling free kick from outside the area left Cesar rooted to the spot.

Three minutes later, Arkaduisz Milik stepped up to score from the penalty spot after the 'keeper's foul on Callejon, taking his tally in two games to three goals.

Vitoria replaced central midfielder Andrea Horta with Eduardo Salvio, and minutes later Napoli stretched their lead to 4-0 after Cesar spilled Callejon's right wing cross to see Mertens convert at the second attempt.

It was the first time in Napoli's history they had scored four goals in major European competition and Mertens was quick to pour the plaudits on Sarri, who was plucked from the relative obscurity of Empoli last year.

"Sarri came into the top level game a bit late, but hats off to him, he's a great coach," said the Belgian.

"Emotionally, Kiev was a big game for me but when you come into the San Paolo and feel the atmosphere it's totally different," added Sarri.

"The fans, the excitement, it's a lot to take in. And when you hear the 'Champions' being sung, it hits you, gets under your skin like a tattoo."

Sarri was delighted at 4-0, and it would have been more emphatic without some slack defending in the final 20 minutes when Goncalo Guedes pounced on Jorginho's poor pass back to round Reina and fire into the roof of the net from a tight angle.

Napoli tired in the final five minutes and when Salvio's pace took him past Ghoulam, a soft touch saw him beat Reina.

It was Benfica's second consolation of the night but might not be enough to help a group campaign that started with a 1-1 draw at home to Besiktas.

"There were seven or eight minutes in which we completely lost focus," admitted Vitoria.

Having been held 1-1 by Besiktas at home a fortnight ago, Benfica's chances of making the knockout phase have dimmed significantly.

But after Dinamo held Besiktas to a 1-1 draw, Vitoria added: "We still believe we can fight to get through the group, but we have to raise our game."

It was Benfica's first defeat of any kind this season and ended a 17-match unbeaten run that stretched back to a first leg defeat to Bayern Munich in the quarter-finals of last season's competition.