The Partenopei sit top of Serie A after the first round of league fixtures, with two goals from Marek Hamsik and a Jose Callejon strike sealing victory, while the home side also had two goals disallowed.
Benitez has overseen a major overhaul in Naples over the summer, bringing in eight new faces in cash deals, as he looks to challenge Juventus for the league title and insists the manner of the win came as no surprise.
"I'm not surprised at the result today," he said after the game. "I saw the team throughout the week and they played very well.
"We don't think about Juventus at this stage, we only think about ourselves. We changed a few players from last season's team but they did just fine and now we can look ahead."
Hamsik was the hero of the day with his double and in a warning to the rest of the division suggested Napoli will get even better as the season progresses, while emphasizing the increased number of attacking options available.
"Today was a game we wanted to win to start the season on the right foot. We don't read anything into it, it means nothing," he said.
"It will be difficult for Gonazlo Higuain to score the same number of goals as Edinson Cavani but we have to help him and try and score 10 goals apiece. Me, Callejon, (Dries) Mertens, (Goran) Pandev can all score goals. We are more competitive than last season and that is good for Napoli."