The Toffees have offered club legend Baines a one-year contract extension.
Baines has made over 400 appearances for the Blues in his 13-year stay at Goodison Park but is still mulling over whether to stay on.
Ancelotti also says there will be another role for him at the club if he doesn't want to continue playing.
The Everton boss said: “I think he is going to give us an answer before Sunday.
“So every decision he is going to take, I'm sure he will be part of this club also in the future.
“Playing or staying at the club.
“His knowledge and experience is important to help this club improve.
“He can be a player but also he can be part of this club. I don't know in which position but for sure he can be part of this club.
“I think he will take a decision this week or at the end of the game. We don't have to wait a lot.
“Before the game I'd like to talk to him about this, as always Leighton is so professional and every decision I take he understands.
“If it is his last game I will give him minutes, I think he deserves it."