The World Cup-winning goalkeeper has fallen behind Diego Lopez in the Santiago Bernabeu pecking order.
A lengthy spell on the sidelines last season with a hand injury forced Real to look elsewhere for shot-stopping talent, and Lopez has made the most of his opportunity.
With there no indication that he will be dropped any time soon, reports have suggested that Casillas is ready to seek a move away from the club that propelled him to superstardom.
The 32-year-old has spent his entire career to date with Real, making close to 700 appearances.
Ancelotti is understandably reluctant to see an iconic figure head for the exits - with Arsenal among those said to be keen - and is confident Casillas will not rock the boat.
He said: "I haven't talked to him about leaving.
"He's a great keeper and a great professional.
"Even if he doesn't play he helps the team, he's a true captain.
"I hope he stays because he's good for the atmosphere. I need to talk to him because it's only fair, but he looks happy to me and he's been very professional."