Napoli owner Aurelio De Laurentiis has branded German outfit Borussia Dortmund "an extraordinary team".
The Italian side begin their Champions League campaign with a home clash against last season's finalists on Wednesday evening.
"Dortmund scare me. They are like a monster with three heads. They are an extraordinary team who play good football and are very personable," he told La Gazzetta dello Sport.
"Both sets of fans are great, and it will make for a great atmosphere on Wednesday. They need their supporters just as much as we need ours."
Napoli currently sit atop Serie A with three wins from three games.
