The Partenopei have been drawn against the Welsh club in the Round of 32 and Spanish boss Benitez is expecting a tough two-legged encounter with Michael Laudrup's men.
"It's a challenging opponent," Benitez told reporters. "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."
Napoli head to the Liberty Stadium for the first leg on February 20 before hosting the Swans at Stadio San Paolo on February 27.
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