Napoli dropped into the Europa League after being eliminated from the Champions League with 12 points – the highest total for a club not progessing in the competition.
The Serie A club will face the Premier League side for the first time in their history and Benitez is well aware of the threat posed by Michael Laudrup's charges, having faced them last season during his Chelsea tenure.
"It's a challenging opponent," the Spaniard admitted. "Over the last few years they have made great progress. They're a growing team that plays good football.
"Michael Laudrup loves possession and they have quality elements such as Michu, who has great talent."
Chairman Aurelio De Laurentiis shared Benitez's views on their next opponents in Europe, but expects his side to progress.
"Swansea is a tough team, but we want to move forward in Europe," he said.
"They are 10th in England and have a good squad. They have made so many strides as a Welsh team.
"We'll have so much respect, but no fear. Benitez knows English football very well and will know how to be able to win."
