Despite collecting one point from their first two Group C matches but the Senegalese international is confident Napoli can bounce back.
“Today was a game that we could have won, we put Spartak back in the game,” Koulibaly said in his press conference.
“By dropping too far back we went into trouble and they took advantage of it. This match teaches us a lot about ourselves and the football we have to play, a more dominant and offensive football.
“Everything is open, there are two games to play with Legia [Warsaw] which are games to win and we hope to be ready. I am confident in our team and I think we will do it.”