That potentially crucial loss at home to their closest foes in the Serie A title race left Juve just a point ahead of Napoli, Kalidou Koulibaly having headed in a dramatic 90th-minute winner.
Clearly despondent at full-time, Juve's players wasted little time leaving the pitch, and failed to applaud the crowd for their support.
As a result, a group of Juve fans attended training on Wednesday, demanding to know why the players did not thank the supporters despite having time to congratulate the Napoli players, and Buffon was sympathetic.
According to Corriere della Sera, Buffon said: "It's important for us to have you here.
"You were right to come here. If we are stuck in this situation, it's because we did something wrong. We want you to be proud of us, until the end.
"We didn't stop to greet you against Napoli because we were too angry, we went to talk with our opponents because it is our habit to do so, win or lose.
"We didn't stop close to the 'Curva' [a section of the stadium] because we were very disappointed and we didn't realize."