Drinkwater starred in this week's historic 3-0 win Champions League win against Club Brugge.
“I think I have a feeling with my players," said Ranieri. “If I believe he is the best then maybe he feels this as well.
“He is a very good player and what is important is that now he understands he is a good player.
“Last season his mindset seemed to be 'What can I do?' but now he knows because he has won the title, achieved England recognition and has grown up.
“Maybe he didn't believe in himself. I had the impression that he wasn't sure of himself.
“He seemed to have doubts there. Maybe he didn't realise just how good he was. He knows now.
“I try to give all my players confidence. If I choose them, it's because I believe."