This quote is not specific to their Real Madrid careers, but both Carlo Ancelotti and Zinedine Zidane are eternally relevant figures at this club.
Ancelotti, in an interview with Sky Sports, revisited his time coaching Zidane in Juventus in the 1999 - 2000 season. Prior to managing Zidane, Ancelotti had an engrained playing style which he stuck to and rarely deviated from. Zidane was so great it made him rethink his scheme.
“With Zidane, I tried to change my idea about the system. Zidane is the first player who gave me the possibility to change the system and play in a different way. So when I had Zidane, in the first year at Juventus, I played with a system of 3-4-1-2, having [Alessandro] Del Piero and [Filippo] Inzaghi up front and Zidane a little bit behind. The second year, I played with a back four but keeping two strikers in front and one No10 like Zidane.
“Zidane changed my idea about football, I was so focused before Juventus on 4-4-2 and after with Zidane, I changed, I wanted to put him in the best position for him to let him be more comfortable on the pitch.