The Robins secured victory against a strong Potters team in the final minute of extra time when James Collins completed his hat-trick.
"It is obvious that when you win against a side like Stoke City away from home - in a place where teams like Arsenal and Manchester United find it difficult to score even one goal and you are playing in a fortress - it is something special," said the Italian.
"We scored four goals and I don't want to exaggerate, but I think we created another five or six clear chances to score. I don't think they underestimated us and all the congratulations I received from [Stoke manager] Tony Pulis at the end of the game was special for me because he is an experienced and very good manager who has achieved fantastic things with Stoke.
"So I am very proud. It is only one match, but to win 4-3 away from home against Stoke City is a special moment for my club, and I think one of the best performances in this club's history."
The draw for the third round of the League Cup will be made this evening.