Mario Rui warned Napoli “have to concentrate on our own game, as there’s a lot at stake” against Red Star Belgrade.
It kicks off at 20.00 GMT.
The Partenopei will be through to the Champions League Round of 16 if they win tonight and Paris Saint-Germain fail to beat Liverpool.
“We have to concentrate on our own game, as there’s a lot at stake and we must focus on our result,” the full-back told Sky Sport Italia.
“Red Star are in good shape, they had a great performance to beat Liverpool, so we know the kind of match we’re going into.”
Napoli need a boost, as they were held to a 0-0 home draw by Chievo in Serie A on Sunday.
“It’s clear we need to change from the performance against Chievo, but fortunately it was only a few days ago, so we had the opportunity to immediately get our heads on this game.”