Napoli's Ezequiel Lavezzi will undergo tests on Thursday in an effort to ascertain how serious his injury is.
The Argentine picked up a problem in the second half of the Manchester City tie which forced him to be replaced by Blerim Dzemaili in the 57th minute.
"I have to wait for the doctor to tell me what the situation is," he noted. "My ankle is very painful, but I hope it's nothing too serious."
The South American is hoping to be fit for the big Serie A game of the weekend as the Azzurri host champions Milan.
Napoli underlined their strength on Wednesday when impressing in their Champions League debut by drawing 1-1 at City.
"We could've scored when I hit the crossbar, but these things happen," added the forward. "We had a good performance and took the right approach.
"City are a strong team, but we showed character, treated the game with the right level of respect and managed to cause Manchester a lot of problems."