Benitez said: "I don't like to talk about this player or that player being the best in the world, but Steve's one of them.
"I've been working with him for the last eighteen months and I can see the improvement he has made in that time. Whatever position he has played in, he's done a very good job and played his part for the team.
"Players can always improve and so it would be wrong to say he's the complete player, but he's very close.
"He is getting better all the time and I'm sure his best years are still ahead of him."