The Stadio San Paolo outfit have won 13 of 17 league games this season with just a defeat so far.
And Koulibaly who has featured in 16 league games this campaign with three goals to his name, stated that he is pleased with the Partenopei’s performance.
But the 27-year-old has named the teams the Naples outfit should look out for as they continue the chase for their first Serie A title since 1990.
“We’re very satisfied with what we’ve done so far,” Koulibaly told Il Mattino.
“First place is worth a lot, but we know the road ahead is long. We need to do our best and win as many games as possible, starting with Sampdoria on Saturday.
“At the moment these five teams are definitely in the running for the Scudetto. Sampdoria are going through a difficult period, but they play in a similar way to us and they’ll be a difficult team to face.
“These are the games we have to win though, because that’s the only way to aim for the Scudetto. They’ve been waiting for it in Naples for a long time.
“We hope we’re still first in March/April.”
Napoli continue their title race on Saturday when they host Sampdoria at the Stadio San Paolo.