Bale has been linked with a summer move to Real.
Zidane told Sky Sports: "This year the player who's impressed me most is not actually playing in the Champions League. He's playing in 'the other cup', and that's Bale.
"He's unique. He makes things look easy, his pace is frightening, his acceleration is unbelievable because of his ability to go through the gears in very little space.
"Plus, he's very good technically which is also important. We mustn't forget that he plays football very well!
"And he's really impressed me. I've seen him two or three times live, including recently at Lyon, which wasn't necessarily his best game, but where every time he got the ball he can surprise you."