Coach Gennaro Gattuso watched from the sidelines with a black patch over his right eye as an out-of-sorts Napoli fell to consecutive defeats for the first time this season following a 2-0 loss at Lazio in Serie A on Sunday.
"Rino is fighting this eye problem and will have it for a few more days, then hopefully everything will return as before," his assistant Luigi Riccio who attended the press conference in Gattuso's place said after the match.
Gattuso, 42, suffers from ocular myasthenia, an auto-immune disease that affects the muscles which control the eyes, and which flared up several days ago.
Fifth-placed Napoli suffered against Lazio, in eighth, who are their direct rivals for the Champions League places.
Napoli were playing without injured Nigerian striker Victor Osimhen and club record scorer Dries Mertens, with captain Lorenzo Insigne suspended for insulting the referee in their defeat at Inter Milan last time out.
Napoli were never really in the game with Lazio goalkeeper Pepe Reina barely tested apart from a Fabian Ruiz strike after 18 minutes.
Ciro Immobile headed home the opener in the ninth minute, with the Italian forward setting up Luis Alberto for the second on 55 minutes following a blunder in the Napoli defence.
"A step backwards compared to many other games, it wasn't us, lacklustre, ugly, light, soft," blasted Riccio.
"We're sorry, but this isn't the team we are. We have to react immediately against Torino on Wednesday."
To add to Napoli's woes Hirving Lozano took a blow to his left ankle and is now in doubt for their midweek game at their newly-named Diego Armando Maradona stadium.
Napoli are eight points behind leaders AC Milan as they target their first Serie A titles since the days of club legend Maradona in 1987 and 1990.