However, Emery's Arsenal have struggled on the road since the start of the calendar year and have won just three of their last nine away games in all competitions.
Napoli on the other hand have lost just once at Stadio San Paolo in Serie A all season -- against reigning Italian champions Juventus.
"Fifty-fifty, it's not changed for me. We played the first leg at home and we won," Emery told a news conference on Wednesday. "That's a normal result.
"But when you play here against Napoli, they can beat you, it's a possibility because they are very strong at home.
"(They will test us) tactically and with this atmosphere here they are going to play with courage. They are ready to play with their head and intelligence."
Arsenal will be without on-loan midfielder Denis Suarez after the club confirmed he stayed in London for treatment on a groin problem.
(Reporting by Hardik Vyas in Bengaluru; Editing by Toby Davis)
