Juve have now conceded seven goals in two games since the New Year.
"We are working on a long-term project," assured Del Neri. "Of course these defeats are painful, but they also help you to learn. We must work on analysing the games carefully.
"We're going through a difficult situation, as we lost important players like Fabio Quagliarella, Vincenzo Iaquinta and Felipe Melo, who would've given the side more quality. There are some problems and we have to try to eliminate them."