With his troops trailing 1-0 after last week's first leg at the Dragao, the Spanish coach feels that the outcome of the return fixture will hinge on who scores the opening goal
The Partenopei succumbed to a solitary strike from Jackson Martinez in the first leg of their last 16 tie with the Portuguese champions at the Dragao last week.
Benitez, therefore, believes that the first goal in Naples will be crucial, as he feels that it would be extremely difficult for his troops to score three times against a side for whom he has the utmost respect.
"Porto have a very strong team with great qualities," he told reporters on Wednesday. "They have players that can make the difference.
"We do not know if they will sit back against us or attack us, but we are ready for anything.
"The goal for us is to continue to create in attack to have a more solid defence.
"[On Thursday] we must score against a very strong team, one of the strongest in Europe.
"We know that if we score a goal, we will have more time. But we must think only of the opening goal, not the second or third.
"We must play without haste but also without pausing. We must go onto the field thinking of scoring.
"We will play with trust in ourselves, like we did in the Champions League."
Benitez also admitted that he is hoping home advantage will ultimately prove decisive in Napoli's bid to progress to the quarter-finals.
"To go into a Europa League game with 50 to 60,000 people at the stadium is very positive and important for the growth of the club," he enthused.
"Our primary goals is second place [in Serie A], but now the most important game is the one [on Thursday].
"The San Paolo can make the difference."