Benfica have shown themselves to be one of the best teams in the Champions League, Napoli head coach Maurizio Sarri has warned.
The Serie A side host Benfica on Wednesday in their second Group B game, having begun their campaign with a 2-1 triumph over Dynamo Kiev.
Napoli have never lost at home to Portuguese opposition and are firm favourites to take all three points, with Benfica having been held to a 1-1 draw by Besiktas on matchday one.
But Sarri believes Benfica proved they are a team to be admired in last season's quarter-finals, when they narrowly lost 3-2 to Pep Guardiola's Bayern Munich after a 2-2 draw in the second leg at the Estadio da Luz.
"The lads are aware of how difficult this game will be for us but they are ready," he said.
"Benfica are a strong side, they have technique, they love to have possession during games and they have quality, so we're talking about one of the strongest sides in Europe.
"It's not easy to win the ball back quickly from them, because they have technique and the ability to dribble. You can't force them into an error.
"They build well from the back, they have strong defenders, they're well-organised and have a great midfield. Then they have [Eduardo] Salvio and Pizzi on the wings.
"But that's not all, they are also very organised. They are a top European side who scared Bayern last season. We have to think of doing our best without asking ourselves too many questions."
Napoli have started the season brightly, winning five and drawing two of their seven matches to date and conceding just twice in their last five.
Such a run has been in contrast to their performances in the latter part of 2015-16, when inconsistent form saw them exit the Europa League and the Coppa Italia, as well as surrender their Serie A title pursuit to eventual champions Juventus.
Sarri, however, has dismissed claims that they allowed their standards to slip drastically as media exaggeration.
"The drop in performance last year is an invention from the journalists," he said. "We got 41 points in the first half of the season and 41 points in the second, so we didn't drop-off that much.
"Maybe in February we lacked a bit of verve, but over 10 months of a season that can happen."