Benitez has praised his vice-captain ahead of his milestone game tomorrow afternoon.
"It's like I said with Stevie recently - to be at one club for such a long time and to play 600 games is absolutely amazing and shows the passion and commitment," said the boss.
"Before I came here, I watched a lot of games and was analysing the players and Carra always stood out as you could see he was a clever player.
"He wanted to be a central defender and he was keen to learn; you can see that he has improved and improved every single year. He is a top professional.
"That is the difference between him and other players. Some have different qualities but he analyses, he reads the games well and he can adapt to different situations.
"It can be difficult for defenders to get recognition. For strikers and midfielders, it is easy because everyone can see their goals.
"With defenders, you tend only to see own goals and mistakes getting highlighted, so it is more difficult to keep up their profile.
"But during the time I have been here, you can only say that Carra has done really well; he is one of the best defenders in England - and I'm sure he will continue to do well."