Ezequiel Lavezzi is in Napoli's squad to face Milan on Sunday night, but it's a race against time to recover.
‘Pocho' limped off during the 1-1 Champions League draw away to Manchester City on Wednesday with a badly bruised ankle.
Coach Walter Mazzarri said he would wait for the response from the club medics before making a decision.
Lavezzi is included in the 19-man squad for Sunday evening's game, but it remains to be seen whether he will even be on the bench.
It is a race against time for the Argentine to feature with Marek Hamsik and Edinson Cavani.
Options to replace Lavezzi include Mario Alberto Santana, Goran Pandev, Juan Zuniga and Giuseppe Mascara.
Napoli squad: De Sanctis, Rosati, Aronica, Campagnaro, Cannavaro, Fernandez, Grava, Dossena, Dzemaili, Gargano, Hamsik, Inler, Maggio, Zuniga, Cavani, Lavezzi, Mascara, Pandev, Santana