Two goals in injury-time to Alessandro Matri and Daniele Conti won the points for Cagliari against a Napoli team that had been leading until the 93rd minute thanks to a Marek Hamsik strike.
Ballardini said: "It makes no difference winning in Serie A or in a youth team championship, the feeling is the same. I am happy for the team, the staff and the fans, this is a day for them.
"The crowd helped us so much and gave us the push to keep going until the end. Perhaps you don't believe me, but I was relaxed because I saw the team attacking and creating a series of chances, so sooner or later we had to score."