The Italian says he had to abandon his usual tactics and adopt a diamond formation, typically 4-1-2-1-2, that would give Zidane the freedom to show what he could do.
"Before, when I started to train, I had an identity which I put on my teams," said Ancelotti said.
"I didn't look at the characteristics of my players. I wanted to play 4-4-2 for the first two years. After that, I changed my ideas. It changed at Juventus - Zidane didn't want to play on the left, but in the centre, so I changed my formation for my players.
"There is not a winning shape: you can play 4-4-2, 4-3-1-2. Now I look at the skills and characteristics of my players and put the right shape in the team for them."