Barcelona's Busquets wary of individual Real Madrid quality
Barca go into the game eight points clear of Real.
"Iker Casillas is one of the best goalkeepers in the world and has had a phenomenal career," Busquets said.
"Sergio Ramos has great qualities and will play wherever you play, with or without the ball. And he's a great marker.
"Pepe is a key player and very powerful, Xabi Alonso is the one who directs and manages Madrid's game. His long balls behind the opponents' defence are dangerous and create a lot for Madrid.
"We have to try to stay one step ahead of him, it will not be easy.
"All in all, they're a great team, great players and we have to be at our best."