The Partenopei coach was disappointed his team could not score the away goal they craved, but is confident his charges can secure a victory in the return tie
Jackson Martinez scored the only goal of the game for the Portuguese Champions League dropouts, ensuring a cushion for Luis Castro's men ahead of the return leg at the Stadio San Paolo.
Despite the defeat, Benitez was looking ahead with an optimistic outlook but accepted the Partenopei's gameplan at the Estadio do Dragao was not properly executed.
"One-nil is a bad result for us, but we can win 2-0 at the San Paolo," the Spaniard told Sky Sport. "Our idea was to do well defensively and start creating dangers as well.
"We did not do this at first but in the second half we were able to do it and we could have scored a goal. I saw a couple of situations in the first half when we had to be more precise and do damage.
"Playing the second leg at our home stadium can make a difference, but Porto are strong in attack which can make the difference, too. It will be difficult, but we can do it."
Benitez guided Chelsea to Europa League glory last year to bag the Blues' second European trophy in as many seasons following their Champions League triumph under Roberto Di Matteo in 2011-12.