Serena believes Kolo Muani is changing Juve's season after Sunday's win against Inter Milan.
He told Radio Rai: "I think Juve cannot think about winning the Scudetto.
"(Thiago) Motta must think about building a game and a common spirit that I think he is finding. Kolo Muani, from an individual point of view, is a star: he has speed, technique and great will. I think he is an individualist: yesterday he made the assist, but only because he could not do anything else.
"In the first half he did not give a great ball to Nico Gonzalez, because he sees the goal, wants the goal and lives for that and at this moment he is a point of reference, Juve needed someone up front who knows how to create opportunities. In the future he will have to change this selfish tendency, also penalised by his experience at PSG, where Luis Enrique wants a more total participation of the striker in the game.
"Juve needed a final point of reference in attack, something that (Dusan) Vlahovic was unable to do."