"He's playing very well and was terrific against Newcastle," Redknapp said. "He's the type of lad you look to build your team around, if you can get him on the ball things can happen.
"It's about getting good people around him with movement to capitalise on what he can do.
"I've spoken to (Croatia boss) Slaven Bilic many times about him. Slaven thinks he's world class and I think he has the ability to be world class."
Modric was in danger of being a high-profile flop under Ramos following his summer move from Dinamo Zagreb worth £16.5million at the time.
He may end up costing more now, given the exchange rate, as Spurs are paying the Croatian club 21million Euros in instalments over four years. Redknapp feels Modric will be worth the money whatever the cost.
"He's only just starting to play in the position he wants, before that he was played wide," Redknapp said. "His position really is behind a striker or behind two strikers if you can play that system with him.
"He is a player who has to be on the move and playing in that position where you can get on the ball. He's not one of those players that you want to stick out wide.
"He's got to be in a position to affect the game and since I've been here we've got him in that position and that is probably why his form has been good."