Stefano Pioli's side are in tremendous form and stretched their winning streak to nine consecutive games in all competitions with a 3-0 victory against Pescara on Saturday.
They must contest a Coppa Italia quarter-final against Lazio prior to their upcoming meeting with Juve, but Buffon remains wary of the Nerazzurri, who came out on top when the sides met last September.
"Now we'll play against Inter, whose form right now is better than Barcelona and Real Madrid's," the 39-year-old told Sky Italy after his side's win over Sassuolo.
"It will be difficult, we respect them. They are strong and they proved it in the first match of the season."
Juventus' win over Sassulo at the Stadio Citta del Tricolore came thanks to goals from Gonzalo Higuain and Sami Khedira.