Juve have won the title in each of the last six seasons but find their dominance under severe threat, says the former Italy star
Gianfranco Zola expects next month's clash between Napoli and Juventus to prove decisive in the race for the Scudetto.
Napoli saw their lead at the top of Serie A reduced to just one point on Saturday when they lost 4-2 at home to Roma, Juve having beaten Lazio 1-0 away earlier in the day.
Zola was a member of the Partenopei squad that last won the domestic title in 1989-90, and he had considered Maurizio Sarri's side favourites to emulate that feat this term.