Jackson Martinez's second-half strike on Thursday night gave Porto the upper hand in the last-16 match-up, and Napoli are now tasked with scoring at least once in next week's return leg if they are to progress to the last eight.
Benitez was not happy with the 1-0 scoreline but feels 2011 Europa League winners Porto will struggle to concentrate in what promises to be a hostile atmosphere at the San Paolo.
"We will go all out for qualification at the San Paolo, the encouragement of our fans will make all the difference," he told Napoli's official website.
"One-nil is certainly not a positive result but we have demonstrated that we're able to play well against a strong side like Porto.
"Having seen how we played last night, I believe we have the potential to score more than one goal at the San Paolo."
Porto's interim head coach Luis Castro, who replaced Paulo Fonseca last week, has enjoyed a fine start in the Estadio do Dragao dugout.
His first league game in charge saw Porto beat Arouca 4-1 while he feels the reinvigorated Dragons should have scored more goals past a Napoli side they dominated for most of Thursday night's match.
"We could have won by 2-0, as we did score two goals, but one of them was disallowed," he told fcporto.pt.
"We did what we aimed to do, winning without conceding, which will also be an important approach to the second leg.
"The tie is going to be played until the last minute of the next game.
"We realised that everything we thought about Napoli is true. They are quick going forward when they get the ball.
"This match confirmed that the tie will be close, but today we were better and won fair and square."