Napoli coach Walter Mazzarri says they'll need a "perfect" performance to defeat Champions League opponents Chelsea.

The Azzurri were drawn with Chelsea yesterday.

"Chelsea are one of the strongest sides in Europe," said Mazzarri.

"After a period of crisis, they are rediscovering their continuity thanks to champions such as Didier Drogba.

"They beat Manchester City in their last game, a side who are dominating the Premier League, so that must mean something.

"The first game between us is at home, therefore the tie at Stamford Bridge will decide qualification. If we want to make it through then we'll have to be perfect."