The Italian giants will be without a key figure when they welcome the Spanish champions to Stadio San Paolo next week
Koulibaly sustained a hamstring injury during a 2-1 home defeat to Parma on December 14, which has kept him on the sidelines for the last two months.
The 28-year-old made his long-awaited return to the pitch on February 9, playing the full 90 minutes of a 3-2 loss away at Lecce, but he was an unused substitute during a Coppa Italia victory over Inter three days later.
Gattuso opted to leave him out of his squad completely for Sunday’s win at Cagliari, and the Italian boss has now delivered a definitive update on the centre-back’s fitness.
Napoli will be back in action against Brescia at Stadio Mario Rigamonti on Friday, but Koulibaly will not travel with the rest of the squad, with Gattuso confirming he will also miss a huge last-16 first-leg clash with Barca .
Gattuso told a press conference: “Koulibaly against Barcelona? He still has swelling, I prefer to stop him for 7-10 days and then evaluate how he feels physically.”
Hirving Lozano and Allan will both be available for Napoli’s latest Serie A outing, with Arkadiusz Milik also back in the fold after recovering from illness.
Gattuso’s men must beat Brescia in order to keep their faint hopes of Champions League qualification alive, having already fallen 12 points behind fourth-placed Atalanta.
Napoli could also gain entry to next season’s competition by winning the trophy come May, but they are heavy underdogs heading into their clash with Barca.
The Blaugrana reached the semi-finals in 2018-19, while Napoli exited in the group stages, but they progressed to the last 16 in impressive fashion this time around.
Napoli finished second in Group E by just a single point behind reigning champions Liverpool, whom they beat 2-0 at Stadio San Paolo and held to a 1-1 draw at Anfield.
Gattuso insists his side will not be looking past Brescia, though, as he expects a similar challenge to the one Cagliari posed his side last weekend.
“Tomorrow’s game against Brescia is the priority,” he added. “We’re expecting a similar match to the one against Cagliari. We certainly must be fully focused heading into it”