Former AC Milan manager Carlo Ancelotti believes that AC Milan made a huge mistake when they let playmaker Andrea Pirlo leave for title rivals Juventus.

Pirlo was the heart of the AC Milan side which won the Scudetto and Champions League on several occasions in the 2000s but was allowed to leave the club on a Bosman ruling in the summer after his contract was not renewed.

The 32-year-old has been the heart of Juventus since then and is arguably the best player in the Serie A at the moment, orchestrating the Bianconeri's title charge with astute playmaking in the middle.

Ancelotti felt that AC Milan made a huge mistake in letting such an important player like Pirlo join their title rivals.

"I would never have let him go," Ancelotti told Mediaset Premium. "Or at most, I would have let him join Chelsea or PSG, where he could play under me.

"Perhaps Pirlo wanted a better contract and Milan did not want to give it to him. So maybe he joined Juventus to get that."

The 52-year-old then continued to talk about the plethora of talented midfielders he managed, which included the likes of Pirlo, Zidane, Clarence Seedorf, Kaka and Gennaro Gattuso.

"The thing I am most proud of was the invention of the formation which looks like a Christmas tree: I had so many good midfielders and that was key to make them all play together, while giving the team a unique balance.

"From my years at Juventus, I remember a lot of things. For starters I remember [Zinedine] Zidane, who was absolutely the best player I have ever coached," Ancelotti said.

"My regret, if I could put it this way, was that he rarely showed in matches the monstrous things he did in training."

Pirlo recently scored his first goal for Juventus over the weekend against Catania. He will likely line up against Milan this weekend, where he is still highly regarded as a cult figure of their successes in the earleir decade.