Napoli full-back Faouzi Ghoulam will spend another month on the sidelines after undergoing surgery on a fractured patella in his right knee.
Ghoulam has been out of action for Napoli since tearing the anterior cruciate ligament in the same knee during the 4-2 Champions League group stage defeat to Manchester City on November 1.
The Algeria international returned to first-team training last month but suffered a setback in his recovery and required an operation.
"Ghoulam was operated on at Villa Stuart by Professor [Pierpaolo] Mariana due to a transverse fracture of the right patella," a Napoli statement announced.
"The intervention was perfectly successful. Faouzi will start rehabilitation [on Saturday]. He will be evaluated in 15 days and should return to the training pitch in a month."
Napoli slipped to second in Serie A after Juventus beat Fiorentina 2-0 on Friday, but Maurizio Sarri's side can return to the summit with victory over Lazio on Saturday.