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."
Napoli on Friday morning announced that full-back Christian Maggio had been admitted to hospital suffering from a pneumothorax.
A statement published on Napoli's website said a drain had been fitted to the 32-year-old's chest to remove an abnormal build-up of air from his chest, one caused by a knock he took during the warm-up for Thursday's match.
Maggio, who complained of discomfort as soon as Napoli's return flight landed in Italy, will remain under observation for 24 hours and could return home on Saturday, according to the club.