Aaron Ramsey’s strike and an own goal from Senegal international Kalidou Koulibaly gave the Gunners a 2-0 advantage at the Emirates Stadium over the Italian side.
Elneny has made six appearances in the European competition this season and he is not expecting an easy ride for the Gunners at the Stadio San Paolo.
“There are still 90 minutes to play,” Elneny posted on Instagram.
“Looking forward to a very intensive match tomorrow night. Now it’s time to take off Napoli.”
The Afcon hosts will begin their campaign for an eighth continental trophy with a fixture against Zimbabwe at Cairo International Stadium on June 21 before locking horns against DR Congo and Uganda on June 26 and 30 respectively at the same venue.