The Colombian has shone since his August arrival from Ajax.
"We expect more from him," Pochettino said. "But I am so happy with him. He is doing well, very well, he's only 21 years old but he shows more maturity and he's so aggressive when he's marking, his concentration and then with the ball he's good, but I think he can improve.
"There is a massive [scope] to improve potentially, it's massive for him. In only a few months, he's showing he's doing fantastic job for us.
"He's so clever, and he's very humble, and he's very open to learn.
"He's a player when you tell something his reaction is to be open, and be critical with himself, and that is a massive skill from a player, when he's so open to improve."