Napoli coach Walter Mazzarri refuses to accept they're favourites in their Champions League clash with Chelsea.

The Partenopei welcome Chelsea to the Stadio San Paolo on Tuesday evening in the first leg of their Champions League Round of 16 clash.

"Are Napoli the favourites? I don't agree with that," Mazzarri told Sky Sport Italia.

"Chelsea will put all their attention on to the Champions League and have players accustomed to these fixtures. It's going to be a terrible test for us, as you cannot ignore the qualities of our opponents.

"Napoli have to do something exceptional, but then we've been doing that for a while."